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I have an app that utilizes a TSL 1128 reader to read RFID tags. It uses the IASCIICommandResponder Library to communicate with the reader.
I have one Class called orderFullfill.java that is responsible for the Listview and updating the UI for this class. Th
The Reader functionality is set up in another class (orderResponder.java) that implements this IASCIICommandResponder, so that it can run in the background whilst orderFullfill shows the changes made to the ArrayList.
I have tried passing the Arrayadapter from orderFullfill.java to orderResponder to call notifyDataSetChanged(); but that has no effect. I have to call addPigNumber() method on a button click to update my listview.
Ideally I need the listview to update when a new tag is added to the list. Please can someone help me apply notifyDataSetChanged() in the right place so that when I can a tag it will add to the list automatically. I am very grateful for any help that is received.
public class orderFullfill extends AppCompatActivity implements PopupMenu.OnMenuItemClickListener {int where; public static ArrayList scannedPigs = new ArrayList<String>();
// The Reader currently in use
private Reader mReader = null;
private boolean mIsSelectingReader = false;
// The model that performs actions with the reader
private TriggerModel mModel;
public static String dispatchweek;
public static String customer;
public static String accountnumber;
public static String supplyfarm;
public static String breed;
public static int numberofpigs;
public static int pigNum;
public static ArrayAdapter<String> adapter;
public static String weekNow;
public static Context mContext;
Switch trick; TextView nameholder;
/**
* #return the current AsciiCommander
*/
protected AsciiCommander getCommander()
{
return AsciiCommander.sharedInstance();
}
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.orderfullfill);
mContext = orderFullfill.this;
addPigNumber();
InventoryCommand iCommand = InventoryCommand.synchronousCommand();
iCommand.setFilterStrongest(TriState.YES);//high power reading
trick = (Switch) findViewById(R.id.scanM2);
trick.setVisibility(View.INVISIBLE);
trick.setChecked(true);
trick.setText(getResources().getString(R.string.lowPowerScan));
trick.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
InventoryCommand iCommand = new InventoryCommand();
//InventoryCommand iCommand = InventoryCommand.synchronousCommand();
if(isChecked)
{
iCommand.setTakeNoAction(TriState.YES);
iCommand.setFilterStrongest(TriState.YES);// low power reading
getCommander().executeCommand(iCommand);
trick.setText(getResources().getString(R.string.lowPowerScan));
}
if(!isChecked)
{
trick.setText(getResources().getString(R.string.highPowerScan));
iCommand.setFilterStrongest(TriState.NO);//high power reading
iCommand.setTakeNoAction(TriState.NO);
getCommander().executeCommand(iCommand);
}
}
});
nameholder = (TextView)findViewById(R.id.nameView);
nameholder.setText(customer);
AsciiCommander.createSharedInstance(getApplicationContext());
final AsciiCommander commander = getCommander();
// Ensure that all existing responders are removed
commander.clearResponders();
// Add the LoggerResponder - this simply echoes all lines received from the reader to the log
// and passes the line onto the next responder
// This is ADDED FIRST so that no other responder can consume received lines before they are logged.
// commander.addResponder(new LoggerResponder());// logcat input
// Add responder to enable the synchronous commands
// commander.addSynchronousResponder();
commander.addResponder(new orderResponder());
// Configure the ReaderManager when necessary
ReaderManager.create(getApplicationContext());
// Add observers for changes
ReaderManager.sharedInstance().getReaderList().readerAddedEvent().addObserver(mAddedObserver);
ReaderManager.sharedInstance().getReaderList().readerUpdatedEvent().addObserver(mUpdatedObserver);
ReaderManager.sharedInstance().getReaderList().readerRemovedEvent().addObserver(mRemovedObserver);
// Create a (custom) model and configure its commander and handler
mModel = new TriggerModel();
mModel.setCommander(getCommander());
mModel.initialise();
ListView scroller = (ListView)findViewById(R.id.listviewD);
scroller.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
PopupMenu popup = new PopupMenu(orderFullfill.this, view);
popup.setOnMenuItemClickListener(orderFullfill.this);
popup.inflate(R.menu.edit_menu);
where = position;
popup.show();
}
});
weekNow = orderResponder.getWeeknow();
}
public ArrayAdapter getAdapter()
{
adapter = new ArrayAdapter<>(mContext, android.R.layout.simple_spinner_item, scannedPigs);
return adapter;
}
public void addPigNumber()
{
adapter = new ArrayAdapter<String>(mContext, android.R.layout.simple_spinner_item, scannedPigs);
TextView counter = findViewById(R.id.editTextNumber);
if(numberofpigs >= 0 )
{
counter.setText("Pigs Left: " +numberofpigs);
if(numberofpigs == 0)
{
counter.setBackgroundColor(Color.parseColor("#BCBDF3E8"));
}
}
ListView scroller = findViewById(R.id.listviewD);
try {
adapter.setDropDownViewResource(R.layout.support_simple_spinner_dropdown_item);
scroller.setAdapter(adapter);
}catch (Exception e)
{
String result ="";
result.equals(e.toString());
}
}
public void orderdetailsOnclick(View view) {
addPigNumber();
AlertDialog.Builder alert = new AlertDialog.Builder(this);
alert.setTitle("Customer Order: " + customer);
alert.setMessage("Account Number: " + accountnumber + "\r\n" +
"Dispatch Week: " + dispatchweek + "\r\n" +
"Supply Farm: " + supplyfarm + "\r\n" +
"Breed: "+ breed + "\r\n" + "Number of Pigs: " + pigNum);
alert.setCancelable(true);
alert.show();
}
#Override
public synchronized void onResume()
{
super.onResume();
addPigNumber();
// Register to receive notifications from the AsciiCommander
LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver, new IntentFilter(AsciiCommander.STATE_CHANGED_NOTIFICATION));
// Remember if the pause/resume was caused by ReaderManager - this will be cleared when ReaderManager.onResume() is called
boolean readerManagerDidCauseOnPause = ReaderManager.sharedInstance().didCauseOnPause();
// The ReaderManager needs to know about Activity lifecycle changes
ReaderManager.sharedInstance().onResume();
// The Activity may start with a reader already connected (perhaps by another App)
// Update the ReaderList which will add any unknown reader, firing events appropriately
ReaderManager.sharedInstance().updateList();
// Locate a Reader to use when necessary
AutoSelectReader(!readerManagerDidCauseOnPause);
mIsSelectingReader = false;
displayReaderState();
}
#Override
public synchronized void onPause() {
super.onPause();
// Register to receive notifications from the AsciiCommander
LocalBroadcastManager.getInstance(this).unregisterReceiver(mMessageReceiver);
addPigNumber();
ReaderManager.sharedInstance().onPause();
}
#Override
protected void onDestroy()
{
super.onDestroy();
// Remove observers for changes
ReaderManager.sharedInstance().getReaderList().readerAddedEvent().removeObserver(mAddedObserver);
ReaderManager.sharedInstance().getReaderList().readerUpdatedEvent().removeObserver(mUpdatedObserver);
ReaderManager.sharedInstance().getReaderList().readerRemovedEvent().removeObserver(mRemovedObserver);
// readResponder.tempList = false;
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.reader_menu, menu);
// Reset, connect, disconnect dropdown menu
mResetMenuItem = menu.findItem(R.id.reset_reader_menu_item);
mConnectMenuItem = menu.findItem(R.id.connect_reader_menu_item);
mDisconnectMenuItem= menu.findItem(R.id.disconnect_reader_menu_item);
return true;
}
//----------------------------------------------------------------------------------------------
// ReaderList Observers
//----------------------------------------------------------------------------------------------
Observable.Observer<Reader> mAddedObserver = new Observable.Observer<Reader>()
{
#Override
public void update(Observable<? extends Reader> observable, Reader reader)
{
// See if this newly added Reader should be used
AutoSelectReader(true);
}
};
Observable.Observer<Reader> mUpdatedObserver = new Observable.Observer<Reader>()
{
#Override
public void update(Observable<? extends Reader> observable, Reader reader)
{
}
};
Observable.Observer<Reader> mRemovedObserver = new Observable.Observer<Reader>()
{
#Override
public void update(Observable<? extends Reader> observable, Reader reader)
{
// Was the current Reader removed
if( reader == mReader)
{
mReader = null;
// Stop using the old Reader
getCommander().setReader(mReader);
}
}
};
#Override
public boolean onMenuItemClick(MenuItem item) {
switch (item.getItemId())
{
case R.id.delete_menu:
boolean complete = false;
scannedPigs.remove(where);
numberofpigs = numberofpigs + 1;
//myDB.deleteEntry(scannedItems); -> IF YOU ADD IT TO THE DB REMOVE IT
//select items from the list
addPigNumber();
return true;
case R.id.edit_menu_:
return true;
}
return super.onOptionsItemSelected(item);
}}
orderfullfill.xml
<?xml version="1.0" encoding="utf-8"?><android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="#+id/editTextNumber"
android:layout_width="177dp"
android:layout_height="56dp"
android:layout_marginStart="24dp"
android:layout_marginLeft="24dp"
android:layout_marginTop="80dp"
android:textSize="30sp"
app:layout_constraintBottom_toTopOf="#+id/listviewD"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="1.0" />
<ListView
android:id="#+id/listviewD"
android:layout_width="354dp"
android:layout_height="221dp"
android:layout_marginBottom="12dp"
app:layout_constraintBottom_toTopOf="#+id/scanM2"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.421"
app:layout_constraintStart_toStartOf="parent" />
<Button
android:id="#+id/invoiceMaker"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="12dp"
android:text="#string/makeInvoice"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.75"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/scanM2" />
<TextView
android:id="#+id/nameView"
android:layout_width="333dp"
android:layout_height="52dp"
android:layout_marginLeft="25dp"
android:layout_marginTop="16dp"
android:layout_marginRight="25dp"
android:layout_marginBottom="303dp"
android:textSize="20dp"
app:layout_constraintBottom_toTopOf="#+id/scanM2"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.0" />
<Button
android:id="#+id/orderdetailsBtn"
android:layout_width="119dp"
android:layout_height="54dp"
android:layout_marginTop="68dp"
android:layout_marginEnd="20dp"
android:layout_marginRight="20dp"
android:onClick="orderdetailsOnclick"
android:text="#string/showOrder"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.887"
app:layout_constraintStart_toEndOf="#+id/editTextNumber"
app:layout_constraintTop_toTopOf="parent" />
<Switch
android:id="#+id/scanM2"
android:layout_width="359dp"
android:layout_height="39dp"
android:layout_below="#id/listviewD"
android:layout_marginTop="232dp"
android:text="#string/highPowerScan"
android:textOff="No"
android:textOn="Yes"
android:textSize="27dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.461"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/orderdetailsBtn" />/android.support.constraint.ConstraintLayout>
orderResponder.java -> this is the class that the TSL reader communicates with via ASCII when reading RFID tags. The method Splicer adds the RFID values to the ArrayAdapter then notifyDataSetChanged(); is called. However nothing happens when this method is called from outside orderFullfill.class.
public class orderResponder extends Application implements IAsciiCommandResponder {
public static boolean tempList;
NoteHelper myDB;
public List<String> getReadInput() {
return readInput;
}
public void setReadInput(List<String> readInput) {
this.readInput = readInput;
}
public static List<String> readInput = new ArrayList<>();
#Override
public boolean isResponseFinished() {
return false;
}
#Override
public void clearLastResponse() {
}
#Override
public boolean processReceivedLine(String s, boolean b) throws Exception {
isitMe(s);
return false;
}
public List<String> getList()
{
return readInput;
}
public boolean isitMe (String input)
{
String firstFourChars = "";
//get first 4 chars to see if it contains "EP: "
if(input.length()>4)
{
firstFourChars = input.substring(0,4);
}
else
{
firstFourChars = input;
}
if(firstFourChars.equals("EP: "))// this is the inital identifier for the RFID tags
{
splicer(input);
return true;
}
else
{
return false;
}
}
//takes the last 24 characters removing the 'EP: '
public void splicer (String input)
{ // ArrayAdapter magic = orderFullfill.getAdapter(); THIS Didnt work
orderFullfill.adapter = new ArrayAdapter<String>(orderFullfill.mContext, android.R.layout.simple_spinner_item, orderFullfill.scannedPigs);
String output ="";
output = input.substring(input.length() -24);//maybe take 24 chars
if (orderFullfill.scannedPigs.size() == 0) {
// orderFullfill.scannedPigs.add(output);
orderFullfill.adapter.add(output);
orderFullfill.adapter.notifyDataSetChanged();
orderFullfill.numberofpigs = orderFullfill.numberofpigs - 1;
} else//if the list has values check you are not duplicating the values
{
if (orderFullfill.scannedPigs.contains(output)) {
return;//you are already in the list
} else//you are unique you can join the list
{
// orderFullfill.scannedPigs.add(output);
orderFullfill.adapter.add(output);
orderFullfill.adapter.notifyDataSetChanged();
orderFullfill.numberofpigs = orderFullfill.numberofpigs - 1;
}
}
}
public static String getWeeknow()
{
Date date = new Date();
SimpleDateFormat formatter = new SimpleDateFormat("dd/MM/yyyy");
String dateH = formatter.format(date);
//String dateH = date.toString();
String[] array = dateH.split("\\/");
String output ="";
int month = Integer.parseInt(array[1]);
month = month -1;
Calendar calendar = Calendar.getInstance();
calendar.set(Integer.parseInt(array[2]),month,Integer.parseInt(array[0]));
int weekOfyear = calendar.get(Calendar.WEEK_OF_YEAR);
output = String.valueOf(weekOfyear);
return output;
}}
create orderResponder constructor method. and send your activity(orderFullfill.this) and context to orderResponder as parameter. call like this;
((orderFullfill)activity).adapter = new ArrayAdapter<String>(context, android.R.layout.simple_spinner_item, ((orderFullfill)activity).scannedPigs);
((orderFullfill)activity).adapter.notifyDataSetChanged();
i hope it works.
To start with, I'm still new to Android development, I've asked similar questions here before How to make my Fragment make use of my Activity Data? and How to send data from Activity to Fragment?(Android)
But it seems that most people did not quite understand what I mean, so let me explain better.
Suppose I have a TextView:
<TextView
android:id="#+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="#string/current"
android:textColor="#FF3D19"
android:textSize="24sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
and a Button:
<Button
android:id="#+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="14dp"
android:layout_marginTop="92dp"
android:shadowColor="#FFFFFF"
android:text="Click"
android:textColor="#FF5722"
app:layout_constraintStart_toStartOf="#+id/imageView3"
app:layout_constraintTop_toTopOf="#+id/imageView3" />
in my FirstFragment layout.xml, then i want to call them from my MainActivity i.e current_temp = findViewById(R.id.textView10); to get data i.e current_temp.setText(getString(R.string.blank, response.body().getCurrent().getTemp() + " ℃")); from a weather API and findViewById(R.id.button2).setOnClickListener(new View.OnClickListener() {.
Android Studio will not allow you to just use them like that, so i get this error:
java.lang.NullPointerException: Attempt to invoke virtual method 'void
android.view.View.setOnClickListener(android.view.View$OnClickListener)'
on a null object reference
whenever I run the app. I don't get any other error before running, so the reason is that I've not instantiated any method or maybe callback or interface that will tell the Activity to make use of my fragment's TextViews and Button. So that's what I've been stuck with for days trying to fix, but most people just misunderstood me and started suggesting I should learn ViewModel or LiveData. I watched several tutorials on ViewModel including Codinginflow, they never talked about linking activity to fragment TextViews, they only made a fragment send data to another fragment which is not what I want.
My request is similar to this Android: Can't update textview in Fragment from Activity. NullPointerException tried and failed, So I need step by step procedures on how to apply it.
Full Code:
HomeActivity
public class HomeActivity extends AppCompatActivity {
public static String BaseUrl = "http://api.openweathermap.org/";
public static String AppId = "";
public static String lat = "9.0574";
public static String lon = "7.4898";
// User Timezone name, current time, current temperature, current condition, sunrise, sunset, temperature, pressure, humidity, wind_speed, visibility, UV Index
TextView time_zone, time_field, current_temp, current_output, rise_time, set_time, temp_out, Press_out, Humid_out, Ws_out, Visi_out, UV_out;
ConstraintLayout constraintLayout;
public static int count = 0;
int[] drawable = new int[]{R.drawable.dubai, R.drawable.central_bank_of_nigeria, R.drawable.eiffel_tower, R.drawable.hong_kong, R.drawable.statue_of_liberty};
Timer _t;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
time_zone = findViewById(R.id.textView9);
time_field = findViewById(R.id.textView4);
current_temp = findViewById(R.id.textView10);
current_output = findViewById(R.id.textView11);
rise_time = findViewById(R.id.textView25);
set_time = findViewById(R.id.textView26);
temp_out = findViewById(R.id.textView28);
Press_out = findViewById(R.id.textView29);
Humid_out = findViewById(R.id.textView30);
Ws_out = findViewById(R.id.textView33);
Visi_out = findViewById(R.id.textView34);
UV_out = findViewById(R.id.textView35);
BottomNavigationView bottomNavigationView = findViewById(R.id.bottomNavigationView);
NavController navController = Navigation.findNavController(this, R.id.fragment);
NavigationUI.setupWithNavController(bottomNavigationView, navController);
findViewById(R.id.button2).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
getCurrentData();
constraintLayout = findViewById(R.id.layout);
constraintLayout.setBackgroundResource(R.drawable.dubai);
_t = new Timer();
_t.scheduleAtFixedRate(new TimerTask() {
#Override
public void run() {
runOnUiThread(new Runnable() { // run on ui thread
#Override
public void run() {
if (count < drawable.length) {
constraintLayout.setBackgroundResource(drawable[count]);
count = (count + 1) % drawable.length;
}
}
});
}
}, 5000, 5000);
}
void getCurrentData() {
Retrofit retrofit = new Retrofit.Builder().baseUrl(BaseUrl).addConverterFactory(GsonConverterFactory.create()).build();
WeatherService service = retrofit.create(WeatherService.class);
Call<WeatherResponse> call = service.getCurrentWeatherData(lat, lon, AppId);
call.enqueue(new Callback<WeatherResponse>() {
#Override
public void onResponse(#NonNull Call<WeatherResponse> call, #NonNull Response<WeatherResponse> response) {
if (response.code() == 200) {
WeatherResponse weatherResponse = response.body();
assert weatherResponse != null;
assert response.body() != null;
time_zone.setText(response.body().getTimezone());
time_field.setText(response.body().getCurrent().getDt());
current_temp.setText(getString(R.string.blank, response.body().getCurrent().getTemp() + " ℃"));
current_output.setText(response.body().getCurrent().getWeather().get(0).getDescription());
rise_time.setText(getString(R.string.blank, response.body().getCurrent().getSunrise() + " AM"));
set_time.setText(getString(R.string.blank, response.body().getCurrent().getSunset() + " PM"));
temp_out.setText(getString(R.string.blank, response.body().getCurrent().getTemp() + " ℃"));
Press_out.setText(getString(R.string.blank, response.body().getCurrent().getPressure() + " hpa"));
Humid_out.setText(getString(R.string.blank, response.body().getCurrent().getHumidity() + " %"));
Ws_out.setText(getString(R.string.blank, response.body().getCurrent().getWindSpeed() + " Km/h"));
Visi_out.setText(getString(R.string.blank, response.body().getCurrent().getVisibility() + " m"));
}
}
#Override
public void onFailure(#NonNull Call<WeatherResponse> call, #NonNull Throwable t) {
}
});
}
});
}
}
FirstFragment
public class FirstFragment extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
public FirstFragment() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* #param param1 Parameter 1.
* #param param2 Parameter 2.
* #return A new instance of fragment SecondFragment.
*/
// TODO: Rename and change types and number of parameters
public static FirstFragment newInstance(String param1, String param2) {
FirstFragment fragment = new FirstFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_first, container, false);
}
}
Taking the whole functionality to Fragment won't work too, because retrofit can only be called from Activity. But if you have any solid suggestions, I'll appreciate it.
I suggest you two ways can update data to Text View of Fragment from Activity.
1. Call method update Text View of fragment from Activity (simple way)
Create a method updateData()in fragment class to update data to Text View.
You declare a fragment parameter in activity class and assign to this parameter when add fragment to activity.
When you receive data from api in activity, call fragment.updateData()
fragment_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/temp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:text="TextView"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/hud"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:text="TextView"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/temp" />
<Button
android:id="#+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
home_activity.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<FrameLayout
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
FirstFragment.kt
class FirstFragment : Fragment(R.layout.fragment_layout) {
private lateinit var temp: TextView
private lateinit var hud: TextView
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
temp = view.findViewById(R.id.temp)
hud = view.findViewById(R.id.hud)
}
fun setDataToView(data: WeatherResponse) {
temp.text = data.temp
hud.text = data.hud
}
}
HomeActivity.kt
class HomeActivity: AppCompatActivity() {
private val fragment = FirstFragment()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.home_activity)
addFragment()
fragment.view?.findViewById<Button>(R.id.button2)?.setOnClickListener {
getCurrentData()
}
}
private fun addFragment(){
val fm = supportFragmentManager
fm.beginTransaction().replace(R.id.container, fragment, "FirstFragment").commit()
}
private fun getCurrentData(){
//Your retrofit code in here. I only show code in onResponse()
//.....
#Override
public void onResponse(#NonNull Call<WeatherResponse> call, #NonNull Response<WeatherResponse> response) {
if (response.code() == 200) {
fragment.setDataToView(response)
}
}
//....
}
}
2. Using ViewModel
Create a SharedViewModel class with a livedata parameter.
In activity, on onCreate() you create a SharedViewModel paramerter like below:
SharedViewModel viewModel = new SharedViewModel(this).get(SharedViewModel .class);
In fragment, on onActivityCreated() you create a SharedViewModel paramerter like below:
SharedViewModel viewModel = new SharedViewModel(requireActivity()).get(SharedViewModel .class);
Finally, you have same ViewModel instance in activity and fragment because both using activity context. When you receive data from api, update your livedata parameter in activity, fragment also receives livedata parameter onChanged event and then you can update Text View.
There are many ways to achieve what you are tying to do, I will be using RxJava.
Add RxJava in your project:
implementation 'io.reactivex.rxjava3:rxandroid:3.0.0'
Create a POJO class to hold your data which then later can be transferred using RxJava bus
public class WeatherReport {
private String time_zone;
private String time_field;
private String current_temp;
private String current_output;
private String rise_time;
private String set_time;
private String temp_out;
private String Press_out;
private String Humid_out;
private String Ws_out;
private String Visi_out;
public String getCurrent_output() {
return current_output;
}
public String getCurrent_temp() {
return current_temp;
}
public String getHumid_out() {
return Humid_out;
}
public String getPress_out() {
return Press_out;
}
public String getRise_time() {
return rise_time;
}
public String getSet_time() {
return set_time;
}
public String getTemp_out() {
return temp_out;
}
public String getTime_field() {
return time_field;
}
public String getTime_zone() {
return time_zone;
}
public String getVisi_out() {
return Visi_out;
}
public String getWs_out() {
return Ws_out;
}
public void setCurrent_output(String current_output) {
this.current_output = current_output;
}
public void setCurrent_temp(String current_temp) {
this.current_temp = current_temp;
}
public void setHumid_out(String humid_out) {
Humid_out = humid_out;
}
public void setPress_out(String press_out) {
Press_out = press_out;
}
public void setRise_time(String rise_time) {
this.rise_time = rise_time;
}
public void setSet_time(String set_time) {
this.set_time = set_time;
}
public void setTemp_out(String temp_out) {
this.temp_out = temp_out;
}
public void setTime_field(String time_field) {
this.time_field = time_field;
}
public void setTime_zone(String time_zone) {
this.time_zone = time_zone;
}
public void setVisi_out(String visi_out) {
Visi_out = visi_out;
}
public void setWs_out(String ws_out) {
Ws_out = ws_out;
}
}
Create a RxJava bus
import io.reactivex.rxjava3.subjects.BehaviorSubject;
public class RxJavaBus {
private static final BehaviorSubject<WeatherReport> behaviorSubject
= BehaviorSubject.create();
public static BehaviorSubject<WeatherReport> getSubject() {
return behaviorSubject;
}
}
Now from your activity(or from wherever you want to transfer data) use RxBus like this:
WeatherReport weatherReport = new WeatherReport();
weatherReport.setCurrent_output("Some DATA");
weatherReport.setCurrent_temp("Some DATA");
weatherReport.setHumid_out("Some DATA");
weatherReport.setPress_out("Some DATA");
weatherReport.setRise_time("Some DATA");
weatherReport.setSet_time("Some DATA");
weatherReport.setTime_field("Some DATA");
weatherReport.setVisi_out("Some DATA");
weatherReport.setTemp_out("Some DATA");
weatherReport.setWs_out("Some DATA");
weatherReport.setTime_zone("some DATA");
RxJavaBus.getSubject().onNext(weatherReport);
Now you receive your data in your fragment (or wherever you want) like this:
RxJavaBus.getSubject().subscribe(weatherReportFromActivity -> {
weatherReportFromActivity.getCurrent_output();
weatherReportFromActivity.getCurrent_temp();
weatherReportFromActivity.getHumid_out();
weatherReportFromActivity.getPress_out();
weatherReportFromActivity.getRise_time();
weatherReportFromActivity.getSet_time();
weatherReportFromActivity.getWs_out();
weatherReportFromActivity.getTime_zone();
weatherReportFromActivity.getVisi_out();
weatherReportFromActivity.getTime_field();
weatherReportFromActivity.getTemp_out();
});
You're getting a NullPointerException because findViewById(R.id.button2) returns null.
You need to use the fragment's view as the root. The activity.findViewById(...) call uses the activity's view as the root - it's searching activity_home.xml, which doesn't have button2. You can access the fragment's version with fragment.getView().findViewById(R.id._), BUT:
You need to make sure that the fragment has at finished its onCreateView() step in the life cycle. So it has to be launched and inflated. Otherwise, again, the button doesn't exist.
You can make sure your setup is called at the right time and with the view by making it a callback in the fragment life cycle.
//This class can be anywhere - it can be global, private inner, anonymous
class SetupCallback extends FragmentLifeCycleCallback {
#Override
void onFragmentViewCreated(FragmentManager fm, Fragment f, View v, Bundle savedInstanceState) {
ButtonView button = v.findViewById(R.id.button2);
if(button != null) { //This gets called for all fragments so check for null
button.setOnClickListener(new OnClickListener {...});
}
//Repeat for any other elements in the view e.g.
TextView someText = v.findViewById(R.id.someTextView);
someText.setText(R.string.message);
}
}
//In the activity setup - I usually put in onCreate()
SupportFragmentManager.supportFragmentManager = getSupportFragmentManager();
supportFragmentManager.registerFragmentLifecycleCallbacks(new SetupCallback());
//anonymous version:
//supportFragmentManager.registerFragmentLifecycleCallbacks(new FragmentLifecycleCallback() { /*contents of class*/ });
Alternatively you could possibly initialise the Retrofit and Weather service in the Activity, pass them in to the fragment with the constructor or a bundle, then use them to setup the onClickListener in onCreateView().
The RxJava and SharedView approaches are alternatives to having a listener stuck on all the fragment life cycle calls, vs having alternative architectures which make the fragment more reactive.
This needs the androidx.lifecycle.common dependency. If you're using gradle that would be:
dependencies {
implementation 'androidx.lifecycle:lifecycle-common:2.3.0-rc1'
}
Create a class to get retrofit client like below
class RetrofitClient {
private Retrofit retrofit;
private String BASE_URL = "";
public ServiceAPI getRetrofitInstance() {
if (retrofit == null) {
retrofit = new Retrofit.Builder()
.baseUrl(BASE_URL)
.addConverterFactory(GsonConverterFactory.create())
.build();
}
return retrofit.create(WeatherService.class);
}
Now you can call apis inside fragment like this
WeatherService service = RetrofitClient().getRetrofitInstance()
void getCurrentData() {
Call<WeatherResponse> call = service.getCurrentWeatherData(lat, lon, AppId);
call.enqueue(new Callback<WeatherResponse>() {
#Override
public void onResponse(#NonNull Call<WeatherResponse> call, #NonNull Response<WeatherResponse> response) {
if (response.code() == 200) {
WeatherResponse weatherResponse = response.body();
assert weatherResponse != null;
assert response.body() != null;
time_zone.setText(response.body().getTimezone());
time_field.setText(response.body().getCurrent().getDt());
current_temp.setText(getString(R.string.blank, response.body().getCurrent().getTemp() + " ℃"));
current_output.setText(response.body().getCurrent().getWeather().get(0).getDescription());
rise_time.setText(getString(R.string.blank, response.body().getCurrent().getSunrise() + " AM"));
set_time.setText(getString(R.string.blank, response.body().getCurrent().getSunset() + " PM"));
temp_out.setText(getString(R.string.blank, response.body().getCurrent().getTemp() + " ℃"));
Press_out.setText(getString(R.string.blank, response.body().getCurrent().getPressure() + " hpa"));
Humid_out.setText(getString(R.string.blank, response.body().getCurrent().getHumidity() + " %"));
Ws_out.setText(getString(R.string.blank, response.body().getCurrent().getWindSpeed() + " Km/h"));
Visi_out.setText(getString(R.string.blank, response.body().getCurrent().getVisibility() + " m"));
}
}
#Override
public void onFailure(#NonNull Call<WeatherResponse> call, #NonNull Throwable t) {
}
});
}
});
}
Set the data you want to update in the bundle set fragment arguments and call the newInstance then update your views accordingly.
From Activity
FirstFragment.newInstance("yourData","yourData");
In your Fragment
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
I'm new to Android and was working on my first app. I was trying to parse the contents of a Google Sheets spreadsheets, specifically a list of names into a Spinner. I've done so successfully by using an ArrayAdapter with an ArrayList as I can see the options when I expand the Spinner. The problem I'm facing is that the Spinner doesn't show the currently selected item when one is selected. If you try to run my code, you'll see that if you try to click the submit Button, it'll tell you that null is being selected, so I've narrowed down my problem to the currently selected name String not being selected.
Here is my MainActivity class:
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
ArrayList<String> names = new ArrayList<String>();
Spinner spBusinessType;
Button btnsubmit;
ArrayAdapter<String> adapterBusinessType;
String sbusinesstype;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
spBusinessType = (Spinner) findViewById(R.id.spBussinessType);
btnsubmit=(Button)findViewById(R.id.submit);
btnsubmit.setOnClickListener(this);
new DownloadWebpageTask(new AsyncResult() {
#Override
public void onResult(JSONObject object) {
processJson(object);
}
}).execute("https://spreadsheets.google.com/tq?key=1JKU2Vt_gMNUYYALct4m9xElLdpGlQ3N4uhS9qFRzxOQ");
adapterBusinessType = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, names);
adapterBusinessType.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spBusinessType.setAdapter(adapterBusinessType);
spBusinessType.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> adapter, View v,
int position, long id) {
// On selecting a spinner item
sbusinesstype = adapter.getItemAtPosition(position).toString();
System.out.println(sbusinesstype);
// Showing selected spinner item
Toast.makeText(getApplicationContext(),
"Bussiness Type : " + sbusinesstype, Toast.LENGTH_SHORT).show();
}
#Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
}
});
}
#Override
public void onClick(View v) {
Toast.makeText(getApplicationContext(), "You have selected " + sbusinesstype,Toast.LENGTH_SHORT).show();
}
private void processJson(JSONObject object) {
try {
JSONArray rows = object.getJSONArray("rows");
for (int r = 0; r < rows.length(); ++r) {
JSONObject row = rows.getJSONObject(r);
JSONArray columns = row.getJSONArray("c");
String name = columns.getJSONObject(0).getString("v");
names.add(name);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
the AsyncResult interface I'm using to obtain a JSON object from Google Sheets:
public interface AsyncResult
{
void onResult(JSONObject object);
}
the DownloadWebpageTask class that is obtaining and parsing the JSON object:
public class DownloadWebpageTask extends AsyncTask<String, Void, String> {
AsyncResult callback;
public DownloadWebpageTask(AsyncResult callback) {
this.callback = callback;
}
#Override
protected String doInBackground(String... urls) {
// params comes from the execute() call: params[0] is the url.
try {
return downloadUrl(urls[0]);
} catch (IOException e) {
return "Unable to download the requested page.";
}
}
// onPostExecute displays the results of the AsyncTask.
#Override
protected void onPostExecute(String result) {
// remove the unnecessary parts from the response and construct a JSON
int start = result.indexOf("{", result.indexOf("{") + 1);
int end = result.lastIndexOf("}");
String jsonResponse = result.substring(start, end);
try {
JSONObject table = new JSONObject(jsonResponse);
callback.onResult(table);
} catch (JSONException e) {
e.printStackTrace();
}
}
private String downloadUrl(String urlString) throws IOException {
InputStream is = null;
try {
URL url = new URL(urlString);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(10000 /* milliseconds */);
conn.setConnectTimeout(15000 /* milliseconds */);
conn.setRequestMethod("GET");
conn.setDoInput(true);
// Starts the query
conn.connect();
int responseCode = conn.getResponseCode();
is = conn.getInputStream();
String contentAsString = convertStreamToString(is);
return contentAsString;
} finally {
if (is != null) {
is.close();
}
}
}
private String convertStreamToString(InputStream is) {
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}
the activity_main layout file:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:paddingBottom="#dimen/activity_vertical_margin"
tools:context=".MainActivity">
<include layout="#layout/content_main" />
</RelativeLayout>
and the content_main layout file that I put the Spinner in:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
tools:context=".MainActivity">
tools:showIn="#layout/activity_main">
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Select Business Type"
android:textColor="#000000"
android:textSize="20sp" />
<Spinner
android:id="#+id/spBussinessType"
style="#style/Base.Widget.AppCompat.Spinner.Underlined"
android:layout_width="match_parent"
android:layout_height="wrap_content"></Spinner>
<Button
android:id="#+id/submit"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="10dp"
android:text="Submit"
android:textSize="15sp" />
</LinearLayout>
What is causing the adapter to not detect when one of the name strings is being selected? Could it be related to how I'm parsing them from the Google Sheet?
You didnt notify the ArrayAdapter that the data has changed, you originally passed empty Arraylist and upon filling the array list, you have to notifiy the Adapter that data has changed and its time for it to consider that, something like
private void processJson(JSONObject object) {
try {
JSONArray rows = object.getJSONArray("rows");
for (int r = 0; r < rows.length(); ++r) {
JSONObject row = rows.getJSONObject(r);
JSONArray columns = row.getJSONArray("c");
String name = columns.getJSONObject(0).getString("v");
names.add(name);
}
adapterBusinessType.notifyDataSetChanged();
} catch (JSONException e) {
e.printStackTrace();
}
}
That should help.
It would appear no data is being displayed in your Adapter. Nothing can be selected. Your listener code looks fine.
Put adapterBusinessType.notifyDatasetChanged() into the processJson method. Outside the catch or after you add all the data to the list.
Or... replace names.add with adapterBusinessType.add
I want develop application for one website and i want load site posts into RecyclerView. I want show load layout for first entry in application and when load posts data into RecyclerView, hide this layout and show RecyclerView!
I write this codes, but it's not work me and always show emptyLayout.
Main Activity XML :
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/main_root"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/appBackground"
tools:context=".Activities.Main_page">
<include
android:id="#+id/main_toolbar"
layout="#layout/toolbar" />
<android.support.v7.widget.RecyclerView
android:id="#+id/main_recycler"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="#+id/main_toolbar" />
<RelativeLayout
android:id="#+id/main_empty_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:visibility="gone">
<include layout="#layout/empty_page_layout" />
</RelativeLayout>
</RelativeLayout>
MainActivity java :
public class Main_page extends AppCompatActivity {
private static final long RIPPLE_DURATION = 250;
private Toolbar toolbar;
private RelativeLayout root;
private ImageView menu_image;
private RecyclerView main_recyclerView;
private MainAdapter mAdaper;
private List<MainDataModel> dataModels = new ArrayList<MainDataModel>();
private List<MainDataModel> dataModelsArray;
private Context context;
protected Handler handler;
private RelativeLayout loadLayout;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_page);
if (!EventBus.getDefault().isRegistered(this)) {
EventBus.getDefault().register(this);
}
handler = new Handler();
context = getApplicationContext();
loadLayout = (RelativeLayout) findViewById(R.id.main_empty_layout);
toolbar = (Toolbar) findViewById(R.id.main_toolbar);
if (toolbar != null) {
setSupportActionBar(toolbar);
getSupportActionBar().setTitle(null);
}
LoadData();
// Menu
root = (RelativeLayout) findViewById(R.id.main_root);
View guillotineMenu = LayoutInflater.from(this).inflate(R.layout.menu_layout, null);
root.addView(guillotineMenu);
menu_image = (ImageView) toolbar.findViewById(R.id.toolbar_logo);
new GuillotineAnimation.GuillotineBuilder(guillotineMenu, guillotineMenu.findViewById(R.id.menu_layout_image), menu_image)
.setStartDelay(RIPPLE_DURATION)
.setActionBarViewForAnimation(toolbar)
.setClosedOnStart(true)
.build();
// RecyclerView and setData
main_recyclerView = (RecyclerView) findViewById(R.id.main_recycler);
main_recyclerView.setHasFixedSize(true);
main_recyclerView.setLayoutManager(new LinearLayoutManager(this));
mAdaper = new MainAdapter(this, dataModels);
main_recyclerView.setAdapter(mAdaper);
if (dataModels.isEmpty()) {
main_recyclerView.setVisibility(View.GONE);
loadLayout.setVisibility(View.VISIBLE);
} else {
main_recyclerView.setVisibility(View.VISIBLE);
loadLayout.setVisibility(View.GONE);
}
}
#Subscribe
public void onEvent(List<MainDataModel> mainInfoModels) {
mAdaper.add(mainInfoModels);
}
private void LoadData() {
final MainDataInfo dataInfo = new MainDataInfo();
dataInfo.getMainDataInfo(this);
}
}
AsyncTask code:
public class MainDataInfo {
private Context mContext;
public void getMainDataInfo(Context context) {
mContext = context;
new getInfo().execute(ServerIP.getIP());
}
private class getInfo extends AsyncTask<String, Void, String> {
EventBus bus = EventBus.getDefault();
private String ou_response;
private List<MainDataModel> infoModels;
#Override
protected void onPreExecute() {
CustomProcessDialog.createAndShow(mContext);
infoModels = new ArrayList<>();
}
#Override
protected String doInBackground(String... params) {
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
.url(ServerIP.getIP())
.build();
Response response;
try {
response = client.newCall(request).execute();
ou_response = response.body().string();
response.body().close();
if (ou_response != null) {
try {
JSONObject postObj = new JSONObject(ou_response);
JSONArray postsArray = postObj.getJSONArray("posts");
infoModels = new ArrayList<>();
for (int i = 0; i <= infoModels.size(); i++) {
JSONObject postObject = (JSONObject) postsArray.get(i);
int id = postObject.getInt("id");
String title = postObject.getString("title");
Log.d("Data", "Post id: " + id);
Log.d("Data", "Post title: " + title);
//Use the title and id as per your requirement
infoModels.add(new MainDataModel(
postObject.getInt("id"),
postObject.getString("title"),
postObject.getString("content"),
postObject.getString("thumbnail")));
}
} catch (JSONException e) {
e.printStackTrace();
}
}
} catch (IOException e) {
e.printStackTrace();
}
return ou_response;
}
#Override
protected void onPostExecute(String result) {
CustomProcessDialog.dissmis();
if (result != null) {
bus.post(infoModels);
}
}
}
}
when delete emptyLayout from mainActivity, RecyclerView show all posts. when insert this layout (emptyLayout) recyclerView is not VISIBLE and EmptyLayout is not GONE!
How can i fit this problem? tnx all <3
I presume that you don't make your call at the good place because dataModels is always empty.
Indeed, you have to do your call only after the onPostExecute() method on your AsyncTask which loads your data.
You can use an interface (AsyncResponse in example below) to catch the end of AyncTask process.
Here AynscResponse :
public interface AsyncResponse {
void endTask(List<MainDataModel> dataModels);
}
In your AsyncTask :
private AsyncResponse listener;
#Override
protected void onPostExecute(List<MainDataModel> dataModels) {
listener.processFinish(dataModels);
}
Finally in your activity :
// Set by default the visibility
main_recyclerView.setVisibility(View.GONE);
loadLayout.setVisibility(View.VISIBLE);
public void processFinish(List<MainDataModel> dataModels) {
if (dataModels.isEmpty()) {
// Handle error with an empty list
} else {
main_recyclerView.setVisibility(View.VISIBLE);
loadLayout.setVisibility(View.GONE);
}
}
private class getArticles extends AsyncTask<Void, Void, Void> {
String url;
getArticles(String paramUrl) {
this.url = paramUrl;
}
#Override
protected void onPreExecute() {
super.onPreExecute();
mProgressDialog = new ProgressDialog(App.this);
mProgressDialog.setMessage("Učitavanje artikala...");
mProgressDialog.setIndeterminate(false);
mProgressDialog.setCancelable(false);
mProgressDialog.show();
}
#Override
protected Void doInBackground(Void... params) {
arraylist = new ArrayList<>();
try {
Document document = Jsoup.connect(url).get();
Elements els = document.select("ul.category3 > li");
for (Element el : els) {
HashMap<String, String> map = new HashMap<>();
Elements slika = el.select("div.category3-image > a > img");
Elements naslov = el.select("div.category3-text > a.main-headline");
Element datum_noformat = el.select("div.category3-text > div.headlines-info > ul.headlines-info > li").first();
Element datum = datum_noformat.html(datum_noformat.html().replaceAll("Posted ", ""));
Elements desc = el.select("div.category3-text > p");
Elements link = el.select("div.category3-text > a.main-headline");
Element br_kom = el.select("div.category3-text > div.headlines-info > ul.headlines-info > li.comments-icon").first();
map.put("naslov", naslov.text());
map.put("datum", datum.text());
map.put("desc", desc.text());
map.put("ikona", slika.attr("src"));
map.put("link", link.attr("abs:href"));
map.put("brkom", br_kom.text());
arraylist.add(map);
}
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void result) {
listview = (ListView) findViewById(R.id.listview);
adapter = new ArtikliAdapter(App.this, arraylist);
listview.setAdapter(adapter);
mProgressDialog.dismiss();
}
I searched for a lot of codes for onlistview scrolling, but didn't know how to implement it. The problem is, when I call my asynctask, I have an url param,
like new getArticles("http://example.com").execute();
I want to implement an onscrolllistener, but it goes like this, my param is usually set to: http://www.example.com/category/categoryname/, so the second page goes like http://www.example.com/category/categoryname/page/2/, the third one goes http://www.example.com/category/categoryname/page/3/ and so on. Each page has got 7 items that need to be parsed.
How could I implement onscrolllistener, because of the url param?
Thanks in advance.
Base on this link, I have written following solution to add elements ( 30 elements at a time, i.e page size = 30) to listview asynchronously.
Create a class named EndlessListView as follows:
public class EndlessListView extends ListView implements OnScrollListener {
private View footer;
private boolean isLoading;
private EndlessListener listener;// listner
private EndlessAdapter endlessAdapter;// adapter.
private int maxNoOfElement;
public EndlessListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
this.setOnScrollListener(this);
}
public EndlessListView(Context context, AttributeSet attrs) {
super(context, attrs);
this.setOnScrollListener(this);
}
public EndlessListView(Context context) {
super(context);
this.setOnScrollListener(this);
}
public void setListener(EndlessListener listener) {
this.listener = listener;
}
#Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
if (getAdapter() == null)
return;
if (getAdapter().getCount() == 0 || getAdapter().getCount() <= 5)
return;
int l = visibleItemCount + firstVisibleItem;
if (l >= totalItemCount && !isLoading) {
// It is time to add new data. We call the listener
Log.e("LOAD", "DATA");
isLoading = true;
listener.loadData();
}
}
public void setMaxElemnt(int maxNoOfElement) {
this.maxNoOfElement = maxNoOfElement;
}
#Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
}
public void setLoadingView(int resId) {
LayoutInflater inflater = (LayoutInflater) super.getContext()
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
footer = (View) inflater.inflate(resId, null);
this.addFooterView(footer);
}
public void setAdapter(EndlessAdapter adapter) {
super.setAdapter(adapter);
this.endlessAdapter = adapter;
}
public void addNewData(List<Integer> data) {
endlessAdapter.setData(data);
endlessAdapter.notifyDataSetChanged();
isLoading = false;
}
public static interface EndlessListener {
public void loadData();
}
}
After this we have to create the adapter for it,called
EndlessAdapter
public class EndlessAdapter extends BaseAdapter {
private List<Integer> mIntegers;
private Context context;
public EndlessAdapter(Context context) {
this.context = context;
}
public void setData(List<Integer> mIntegers) {
this.mIntegers = mIntegers;
}
#Override
public int getCount() {
if (mIntegers == null)
return 0;
return mIntegers.size();
}
#Override
public Integer getItem(int index) {
if (mIntegers == null) {
return null;
} else {
return mIntegers.get(index);
}
}
#Override
public long getItemId(int arg0) {
// TODO Auto-generated method stub
return 0;
}
class ViewHolder {
TextView textView;
}
#Override
public View getView(int index, View view, ViewGroup viewGroup) {
ViewHolder holder;
if (view == null) {
holder = new ViewHolder();
view = ((LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE))
.inflate(R.layout.rows, viewGroup, false);
holder.textView = (TextView) view.findViewById(R.id.mtext);
view.setTag(holder);
} else {
holder = (ViewHolder) view.getTag();
}
holder.textView.setText(getItem(index) + "");
return view;
}
}
Now in xml of the activity we could use EndlessListView(in com.example.stackoverflow package) as follows :
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<com.example.stackoverflow.EndlessListView
android:id="#+id/endlessListView"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</RelativeLayout>
After this step we need to make following change in the MainActivity
public class MainActivity extends Activity implements EndlessListener {
private EndlessAdapter adapter;
private EndlessListView endlessListView;
private List<Integer> data;
private int gStartIndex = 30;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
endlessListView = (EndlessListView) findViewById(R.id.endlessListView);
adapter = new EndlessAdapter(this);
data = new ArrayList<Integer>();
endlessListView.setLoadingView(R.layout.footer);
// endlessListView.showFooter();
endlessListView.setListener(this);
endlessListView.setAdapter(adapter);
gStartIndex = 0;
fillData(gStartIndex);
}
private void fillData(int startIndex) {
new AsyncLoadData().execute(startIndex);
}
#Override
public void loadData() {
fillData(gStartIndex);
}
private class AsyncLoadData extends AsyncTask<Integer, Integer, Void> {
#Override
protected Void doInBackground(Integer... params) {
int gendIndex = params[0] + 30;
gStartIndex = gendIndex;
/***
* Here you could add your n/w code. To simulate the n/w comm. i am
* adding elements to list and making it sleep for few sec.
* */
for (int i = params[0]; i < gendIndex; i++) {
publishProgress(i);
}
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
#Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
data.add(values[0]);
}
#Override
protected void onPostExecute(Void result) {
endlessListView.addNewData(data);
}
}
}
This custom ScrollListView that I just found has OnBottomReachedListener which you can implement from your Activity or Fragment and receive events when user hits the bottom of the page. You would also need to track the current page and when bottom is hit to download the next page. The latest data should be added to your existing ArrayList and you should call notifyDataSetChanged() on your adapter so ListView can render the new data. You don't have to create new adapter, you just need to update the data source which is your ArrayList.
If you support orientation change you would must to save in onSaveInstanceState() your current page number so when Activity or Fragment is recreated it can continue from correct page. And you would have to keep the ArrayList data source safe of configuration changes because you don't want to downloaded it again. I would suggest using the Fragment with setRetainInstance() set to true to persist ArrayList.
Here is my custom code for keeping data around using RetainFragment:
/**
* A simple non-UI Fragment that stores a single Object
* and is retained over configuration changes.
*/
public class RetainFragment<E extends Object> extends Fragment {
/** Object for retaining. */
private E mObject;
/**
* Empty constructor as per the Fragment documentation
*/
public RetainFragment() {}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Make sure this Fragment is retained over a configuration change
setRetainInstance(true);
}
/**
* Store a single object in this Fragment.
*
* #param object The object to store
*/
public void setObject(E object) {
mObject = object;
}
/**
* Get the stored object.
*
* #return The stored object
*/
public E getObject() {
return mObject;
}
}
Example of RetainFragment usage in your Activity:
FragmentManager fm = getFragmentManager();
mRetainFragment = (RetainFragment<ArrayList>) fm.findFragmentByTag(RETAIN_FRAG);
if (mRetainFragment == null) {
mRetainFragment = new RetainFragment<>();
mRetainFragment.setObject(new ArrayList());
fm.beginTransaction().add(mRetainFragment, RETAIN_FRAG).commit();
}
ArrayList yourArrayList = mRetainFragment.getObject();
// Now your ArrayList is saved accrossed configuration changes
here what you want fist add onscrolllistner to listview
boolean loading_flage = false;
yourlistview.setOnScrollListener(new OnScrollListener() {
#Override
public void onScrollStateChanged(
AbsListView view,
int scrollState) {
// TODO Auto-generated method stub
}
#Override
public void onScroll(AbsListView view,
int firstVisibleItem,
int visibleItemCount,
int totalItemCount) {
final int lastItem = firstVisibleItem
+ visibleItemCount;
if ((lastItem == totalItemCount)
& loading_flage == false) {
//this to prevent the list to make more than one request in time
loading_flage = true;
//you can put the index for your next page here
loadMore(int page);
}
}
});
and then in loading more after loading the page set the loading with false and parse the data add it to the data that you aleardy have
//notify the adapter
adapter.notifyDataSetChanged();
loading_flage = false;
You can achieve by adding the scrolllistener on listview and check condition if list last visible item is last in ArrayList then call the asynctask with incremented page number and update the listview,mean while add the view on listview and after getting the result from server remove the loading more view from the listview like this -
AndroidListViewLoadMoreActivity.java
public class AndroidListViewLoadMoreActivity extends Activity {
ArrayList<Country> countryList;
MyCustomAdapter dataAdapter = null;
int page = 0;
boolean loadingMore = false;
View loadMoreView;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ListView listView = (ListView) findViewById(R.id.listView1);
loadMoreView = ((LayoutInflater)this
.getSystemService(Context.LAYOUT_INFLATER_SERVICE))
.inflate(R.layout.loadmore, null, false);
listView.addFooterView(loadMoreView);
//create an ArrayAdaptar from the String Array
countryList = new ArrayList<Country>();
dataAdapter = new MyCustomAdapter(this,
R.layout.country_info, countryList);
listView.setAdapter(dataAdapter);
//enables filtering for the contents of the given ListView
listView.setTextFilterEnabled(true);
listView.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// When clicked, show a toast with the TextView text
Country country = (Country) parent.getItemAtPosition(position);
Toast.makeText(getApplicationContext(),
country.getCode(), Toast.LENGTH_SHORT).show();
}
});
listView.setOnScrollListener(new OnScrollListener(){
#Override
public void onScrollStateChanged(AbsListView view, int scrollState) {}
#Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
int lastInScreen = firstVisibleItem + visibleItemCount;
if((lastInScreen == totalItemCount) && !(loadingMore)){
String url = "http://10.0.2.2:8080/CountryWebService" +
"/CountryServlet";
grabURL(url);
}
}
});
String url = "http://example.com";
grabURL(url);
}
public void grabURL(String url) {
Log.v("Android Spinner JSON Data Activity", url);
new GrabURL().execute(url);
}
private class GrabURL extends AsyncTask<String, Void, String> {
private static final int REGISTRATION_TIMEOUT = 3 * 1000;
private static final int WAIT_TIMEOUT = 30 * 1000;
private final HttpClient httpclient = new DefaultHttpClient();
final HttpParams params = httpclient.getParams();
HttpResponse response;
private String content = null;
private boolean error = false;
private ProgressDialog dialog =
new ProgressDialog(AndroidListViewLoadMoreActivity.this);
protected void onPreExecute() {
dialog.setMessage("Getting your data... Please wait...");
dialog.show();
}
protected String doInBackground(String... urls) {
String URL = null;
loadingMore = true;
try {
URL = urls[0];
HttpConnectionParams.setConnectionTimeout(params, REGISTRATION_TIMEOUT);
HttpConnectionParams.setSoTimeout(params, WAIT_TIMEOUT);
ConnManagerParams.setTimeout(params, WAIT_TIMEOUT);
HttpPost httpPost = new HttpPost(URL);
//add name value pair for the country code
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
nameValuePairs.add(new BasicNameValuePair("page",String.valueOf(page)));
httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
response = httpclient.execute(httpPost);
StatusLine statusLine = response.getStatusLine();
if(statusLine.getStatusCode() == HttpStatus.SC_OK){
ByteArrayOutputStream out = new ByteArrayOutputStream();
response.getEntity().writeTo(out);
out.close();
content = out.toString();
} else{
//Closes the connection.
Log.w("HTTP1:",statusLine.getReasonPhrase());
response.getEntity().getContent().close();
throw new IOException(statusLine.getReasonPhrase());
}
} catch (ClientProtocolException e) {
Log.w("HTTP2:",e );
content = e.getMessage();
error = true;
cancel(true);
} catch (IOException e) {
Log.w("HTTP3:",e );
content = e.getMessage();
error = true;
cancel(true);
}catch (Exception e) {
Log.w("HTTP4:",e );
content = e.getMessage();
error = true;
cancel(true);
}
return content;
}
protected void onCancelled() {
dialog.dismiss();
Toast toast = Toast.makeText(AndroidListViewLoadMoreActivity.this,
"Error connecting to Server", Toast.LENGTH_LONG);
toast.setGravity(Gravity.TOP, 25, 400);
toast.show();
}
protected void onPostExecute(String content) {
dialog.dismiss();
Toast toast;
if (error) {
toast = Toast.makeText(AndroidListViewLoadMoreActivity.this,
content, Toast.LENGTH_LONG);
toast.setGravity(Gravity.TOP, 25, 400);
toast.show();
} else {
displayCountryList(content);
}
}
}
private void displayCountryList(String response){
JSONObject responseObj = null;
try {
Gson gson = new Gson();
responseObj = new JSONObject(response);
JSONArray countryListObj = responseObj.getJSONArray("countryList");
//countryList = new ArrayList<Country>();
if(countryListObj.length() == 0){
ListView listView = (ListView) findViewById(R.id.listView1);
listView.removeFooterView(loadMoreView);
}
else {
for (int i=0; i<countryListObj.length(); i++){
//get the country information JSON object
String countryInfo = countryListObj.getJSONObject(i).toString();
//create java object from the JSON object
Country country = gson.fromJson(countryInfo, Country.class);
//add to country array list
countryList.add(country);
dataAdapter.add(country);
}
page++;
dataAdapter.notifyDataSetChanged();
loadingMore = false;
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
Make MyCustomAdapter.java as adapter
private class MyCustomAdapter extends ArrayAdapter<Country> {
private ArrayList<Country> countryList;
public MyCustomAdapter(Context context, int textViewResourceId,
ArrayList<Country> countryList) {
super(context, textViewResourceId, countryList);
this.countryList = new ArrayList<Country>();
this.countryList.addAll(countryList);
}
private class ViewHolder {
TextView code;
TextView name;
TextView continent;
TextView region;
}
public void add(Country country){
Log.v("AddView", country.getCode());
this.countryList.add(country);
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
Log.v("ConvertView", String.valueOf(position));
if (convertView == null) {
LayoutInflater vi = (LayoutInflater)getSystemService(
Context.LAYOUT_INFLATER_SERVICE);
convertView = vi.inflate(R.layout.country_info, null);
holder = new ViewHolder();
holder.code = (TextView) convertView.findViewById(R.id.code);
holder.name = (TextView) convertView.findViewById(R.id.name);
holder.continent = (TextView) convertView.findViewById(R.id.continent);
holder.region = (TextView) convertView.findViewById(R.id.region);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
Country country = this.countryList.get(position);
holder.code.setText(country.getCode());
holder.name.setText(country.getName());
holder.continent.setText(country.getContinent());
holder.region.setText(country.getRegion());
return convertView;
}
}
}
Create Country.Java as pojo -
public class Country {
String code = null;
String name = null;
String continent = null;
String region = null;
Double lifeExpectancy = null;
Double gnp = null;
Double surfaceArea = null;
int population = 0;
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getContinent() {
return continent;
}
public void setContinent(String continent) {
this.continent = continent;
}
public String getRegion() {
return region;
}
public void setRegion(String region) {
this.region = region;
}
public Double getLifeExpectancy() {
return lifeExpectancy;
}
public void setLifeExpectancy(Double lifeExpectancy) {
this.lifeExpectancy = lifeExpectancy;
}
public Double getGnp() {
return gnp;
}
public void setGnp(Double gnp) {
this.gnp = gnp;
}
public Double getSurfaceArea() {
return surfaceArea;
}
public void setSurfaceArea(Double surfaceArea) {
this.surfaceArea = surfaceArea;
}
public int getPopulation() {
return population;
}
public void setPopulation(int population) {
this.population = population;
}
}
Create main.xml for main layout
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent" android:layout_height="fill_parent"
android:orientation="vertical">
<TextView android:layout_width="fill_parent"
android:layout_height="wrap_content" android:padding="10dp"
android:text="#string/some_text" android:textSize="20sp" />
<ListView android:id="#+id/listView1" android:layout_width="fill_parent"
android:layout_height="fill_parent" />
</LinearLayout>
Create country_info.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:padding="6dip" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:text="Code: "
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="#+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="#+id/textView1"
android:layout_below="#+id/textView1"
android:text="Name: "
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="#+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="#+id/textView2"
android:layout_below="#+id/textView2"
android:text="Continent: "
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="#+id/textView4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="#+id/textView3"
android:layout_below="#+id/textView3"
android:text="Region: "
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="#+id/continent"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="#+id/textView3"
android:layout_alignBottom="#+id/textView3"
android:layout_toRightOf="#+id/textView3"
android:text="TextView" />
<TextView
android:id="#+id/region"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="#+id/textView4"
android:layout_alignBottom="#+id/textView4"
android:layout_alignLeft="#+id/continent"
android:text="TextView" />
<TextView
android:id="#+id/name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#+id/textView3"
android:layout_toRightOf="#+id/textView3"
android:text="TextView" />
<TextView
android:id="#+id/code"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#+id/textView2"
android:layout_alignLeft="#+id/name"
android:text="TextView" />
</RelativeLayout>
Footer View Text - loadmore.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:gravity="center_horizontal"
android:padding="3dp"
android:layout_height="fill_parent">
<TextView
android:id="#id/android:empty"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:gravity="center"
android:padding="5dp"
android:text="Loading more data..."/>
</LinearLayout>
Don't forget to mention internet permission with -
<uses-permission android:name="android.permission.INTERNET" />
First, you need a OnScrollListener method like this:
private OnScrollListener onScrollListener() {
return new OnScrollListener() {
#Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
int threshold = 1;
int count = listView.getCount();
if (scrollState == SCROLL_STATE_IDLE) {
if (listView.getLastVisiblePosition() >= count - threshold && pageCount < 2) {
Log.i(TAG, "loading more data");
// Execute LoadMoreDataTask AsyncTask
//It reached ListView bottom
getDataFromUrl(url_page2);
}
}
}
#Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount,
int totalItemCount) {
}
};
}
set List View scroll listener by listView.setOnScrollListener(onScrollListener());
I have a full tutorial post HERE! You can visit it!