Develop Reference

How to dynamically add items to GridView Android Studio (Java)

Hello I want to have an Add function that allows me to input items to my GridView
For Background: I have a standard GridView and an XML activity (which contains 2 TextView) that I want to convert to my GridView. I also have a custom ArrayAdapter class and custom Word object (takes 2 Strings variables) that helps me do this.
My problem: I want to have an Add button that takes me to another XML-Layout/class and IDEALLY it input a single item and so when the user goes back to MainActivity the GridView would be updated along with the previous information that I currently hard-coded atm. This previous sentence doesn't work currently
Custom ArrayAdapter and 'WordFolder' is my custom String object that has 2 getters
//constructor - it takes the context and the list of words
WordAdapter(Context context, ArrayList<WordFolder> word){
super(context, 0, word);
}
#Override
public View getView(int position, View convertView, ViewGroup parent){
View listItemView = convertView;
if(listItemView == null){
listItemView = LayoutInflater.from(getContext()).inflate(R.layout.folder_view, parent, false);
}
//Getting the current word
WordFolder currentWord = getItem(position);
//making the 2 text view to match our word_folder.xml
TextView title = (TextView) listItemView.findViewById(R.id.title);
title.setText(currentWord.getTitle());
TextView desc = (TextView) listItemView.findViewById(R.id.desc);
desc.setText(currentWord.getTitleDesc());
return listItemView;
}
}
Here is my NewFolder code. Which sets contentview to a different XML. it's pretty empty since I'm lost on what to do
public class NewFolder extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.new_folder_view);
Button add = (Button) findViewById(R.id.add);
//If the user clicks the add button - it will save the contents to the Word Class
add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
//make TextView variables and cast the contents to a string and save it to a String variable
TextView name = (TextView) findViewById(R.id.new_folder);
String title = (String) name.getText();
TextView descText = (TextView) findViewById(R.id.desc);
String desc = (String) descText.getText();
//Save it to the Word class
ArrayList<WordFolder> word = new ArrayList<>();
word.add(new WordFolder(title, desc));
//goes back to the MainActivity
Intent intent = new Intent(NewFolder.this, MainActivity.class);
startActivity(intent);
}
});
}
In my WordFolder class I made some TextView variables and save the strings to my ArrayList<> object but so far it's been useless since it doesn't interact with the previous ArrayList<> in ActivityMain which makes sense because its an entirely new object. I thought about making the ArrayList a global variable which atm it doesn't make sense to me and I'm currently lost.
Sample code would be appreciative but looking for a sense of direction on what to do next. I can provide other code if necessary. Thank you

To pass data between Activities to need to do a few things:
First, when the user presses your "Add" button, you want to start the second activity in a way that allows it to return a result. this means, that instead of using startActivity you need to use startActivityForResult.
This method takes an intent and an int.
Use the same intent you used in startActivity.
The int should be a code that helps you identify where a result came from, when a result comes. For this, define some constant in your ActivityMain class:
private static final int ADD_RESULT_CODE = 123;
Now, your button's click listener should looks something like this:
addButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
Intent intent=new Intent(MainActivity.this, NewFolder.class);
startActivityForResult(intent, ADD_RESULT_CODE);
}
});
Now for returning the result.
First, you shouldn't go back to your main activity by starting another intent.
Instead, you should use finish() (which is a method defined in AppCompatActivity, you can use to finish your activity), this will return the user to the last place he was before this activity - ActivityMain.
And to return some data, too, you can use this code:
Intent intent=new Intent();
intent.putExtra("title",title);
intent.putExtra("desc",desc);
setResult(Activity.RESULT_OK, intent);
where title and desc are the variables you want to pass.
in your case it should look something like this:
public class NewFolder extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.new_folder_view);
Button add = (Button) findViewById(R.id.add);
//If the user clicks the add button - it will save the contents to the Word Class
add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
//make TextView variables and cast the contents to a string and save it to a String variable
TextView name = (TextView) findViewById(R.id.new_folder);
String title = (String) name.getText();
TextView descText = (TextView) findViewById(R.id.desc);
String desc = (String) descText.getText();
//Save it to the Word class
ArrayList<WordFolder> word = new ArrayList<>();
word.add(new WordFolder(title, desc));
Intent intent=new Intent();
intent.putExtra("title",title);
intent.putExtra("desc",desc);
setResult(Activity.RESULT_OK, intent);
//goes back to the MainActivity
finish();
}
});
}
You should probably also take care of the case where the user changed his mind and wants to cancel adding an item. in this case you should:
setResult(Activity.RESULT_CANCELLED);
finish();
In your ActivityMain you will have the result code, and if its Activity.RESULT_OK you'll know you should add a new item, but if its Activity.RESULT_CANCELLED you'll know that the user changed their mind
Now all that's left is receiving the data in ActivityMain, and doing whatever you want to do with it (like adding it to the grid view).
To do this you need to override a method called onActivityResult inside ActivityMain:
// Call Back method to get the Message form other Activity
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
super.onActivityResult(requestCode, resultCode, data);
// check the result code to know where the result came from
//and check that the result code is OK
if(resultCode == Activity.RESULT_OK && requestCode == ADD_RESULT_CODE )
{
String title = data.getStringExtra("title");
String desc = data.getStringExtra("desc");
//... now, do whatever you want with these variables in ActivityMain.
}
}

Android checkbox checked one variable

I have a many checkbox and I saved in a String if it's checked like this:
String juice = "";
if (apple.isChecked()) {
juice = apple.getText().toString().trim() + " " + etiquetas;
}
if (orange.isChecked()) {
juice = orange.getText().toString().trim() + " " + etiquetas;
}
But when I need in another Activity put the checkbox checked, idk how to checked because I saved in one. I really need to be like this in one variable, because they're instructions for the exam. And thas's my code for the other Activity;
Intent intent = getIntent();
if(intent != null){
String juice_2 = (String) getIntent().getStringExtra("EXTRA_JUICE");
//apple.setChecked();
}

In the current activity, you can use a single String that has multiple juice words separated by a SPACE character.
And at the destination activity, split the string into an array of strings based on the SPACE character, and then set the checkBox value if this array contains your specific juice.
at Activity A:
String juice = "";
if (apple.isChecked()) {
juice = apple.getText().toString().trim() + " ";
}
if (orange.isChecked()) {
juice = orange.getText().toString().trim() + " ";
}
// Going to Activity B
Intent intent = new Intent(ActivityA.this, ActivityB.class);
intent.putExtra("JUICE", juice);
startActivity(intent);
at Activity B:
if (getIntent() != null) {
String juice = getIntent().getStringExtra("JUICE");
if (juice != null) {
String[] splittedJuice = juice.split(" ");
ArrayList list = new ArrayList();
// Convert array into a List
Collections.addAll(list, oldLines);
// Check if the list contains "orange"
if (list1.contains("orange")) {
orange.setChecked(true);
}
if (list1.contains("apple")) {
apple.setChecked(true);
}
}
}

To pass data from one activity to another you can use Intent.putExtra().
The line will look something like this:
intent.putExtra(LABEL, juice);
where: LABEL is a String which allows second activity to find your variable,
juice is your variable.
To resolve the problem you can use something like this:
public class First extends AppCompatActivity {
private final static String LABEL = "juices";
String juice;
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.first);
final CheckBox apple = (CheckBox) findViewById(R.id.apple);
Button nextIntent = (Button) findViewById(R.id.next);
nextIntent.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (apple.isChecked()) {
juice = apple.getText().toString();
}
Intent intent = new Intent(getApplicationContext(), Second.class);
intent.putExtra(LABEL, juice);
startActivity(intent);
}
});
}
}
Second Activity:
public class Second extends AppCompatActivity {
private final static String LABEL = "juices";
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.first);
Intent intent = getIntent();
String dataReceived = intent.getStringExtra(LABEL);
System.out.println("Your string: " + dataReceived);
}
}
Anyway, I would recommend that you pass Boolean values to the next activity without converting them to a String if it's only to check/uncheck Checkboxes in the second layout.
If you have a lot of variables in the first activity you can pass them to the array, send it to the another activity (by the similar way) and iterate to check/uncheck boxes.

Calling new activity from an item inside a recyclerview row

I need to call a new activity, when a button inside one of my recyclerview row elements is called. Each row item in the list contains 4 buttons, one of which needs to open a new activity which will be used to edit the data in that row.
Here is the code for my button so far:
public void onBindViewHolder(CounterLayoutAdapter.ViewHolder holder, final
int position) {
final Counter counter = counterList.get(position);
//counter is a class which holds the data that will be displayed on one
//row
String comment = counter.getComment();
String name = counter.getCounterName();
int number = counter.getCurrentValue();
//LocalDate modifyDate = counter.getLastModifyDate();
Button up = holder.itemView.findViewById(R.id.buttonUp);
Button down = holder.itemView.findViewById(R.id.buttonDown);
Button reset = holder.itemView.findViewById(R.id.buttonReset);
Button edit = holder.itemView.findViewById(R.id.buttonEdit);
Button delete = holder.itemView.findViewById(R.id.buttonDelete);
// code for 4 other buttons goes here
//
edit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
}
});
Since I need the activity that I open to return user inputted data for me, I am using startActivityForResult. However, as far as I can tell, this will only work inside an actual activity class.
So then I tried passing the mainactivity context to my CounterLayoutAdapter class, where all of my button code is. However, the OnBindViewHolder method still cannot access it there. So I tried to pass the context to OnBindViewHolder, but that doesn't work either, as it won't override the abstract class if i do that..
So, how on earth can I call a new activity here?
Alternatively, if there is some other way to get user input into 4 fields and return that input back to the adapter, without calling an activity, that would work as well.
EDIT: viewholder and layout inflation
public static class ViewHolder extends RecyclerView.ViewHolder implements
View.OnClickListener {
private TextView name;
private TextView comment;
private TextView number;
//private TextView date;
public ViewHolder(View itemView) {
super(itemView);
itemView.setOnClickListener(this);
comment = itemView.findViewById(R.id.textComment);
name = itemView.findViewById(R.id.textName);
number = itemView.findViewById(R.id.editTextNum);
//date = itemView.findViewById(R.id.textDate);
}
#Override
public void onClick(View view) {}
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View inflatedView =
LayoutInflater.from(parent.getContext()).inflate(R.layout
.row_layout, parent, false);
return new ViewHolder(inflatedView);
}

You can call startActivityForResult() in adapter class.
Get context in adapter like Context context=holder.up.getContext();
then in your button's OnClickListener do this.
edit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent=new Intent(context,ActivityYouWantToStart.class);
//Pass any extras if you want to.
((Activity)context).startActivityForResult(intent,REQUEST_CODE);
}
});
Then in your activity (which contain this recyclerView) override onActivityResult like this
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == REQUEST_CODE) {//same REQUEST_CODE you used in adapter
if (resultCode == RESULT_OK) {
//Do your thing and get the data you want.
adapter.onDataReady(Data data);//where adapter is your recycler adapter,
//and data is whatever data you want to pass to adapter
//(Data you got from the activityResult, do not confuse it with onActivityResult's parameter 'Intent data')
}
}
}
Finally in your Recycler Adapter class, define onDataReady() function like
public void onDataReady(Data data){
//Update RecyclerView with new data
}
Hope this helps. I once did this, and it works for me. Let me know if you have any problem.

As you see , you do not have to findViewById in onBindViewHolder.
public void onBindViewHolder(CounterLayoutAdapter.ViewHolder holder, final
int position) {
final Counter counter = counterList.get(position);
//counter is a class which holds the data that will be displayed on one
//row
String comment = counter.getComment();
String name = counter.getCounterName();
int number = counter.getCurrentValue();
//LocalDate modifyDate = counter.getLastModifyDate();
holder.edit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
}
});
Then you should init edit in ViewHolder constructor.
public ViewHolder(View itemView) {
super(itemView);
itemView.setOnClickListener(this);
comment = itemView.findViewById(R.id.textComment);
name = itemView.findViewById(R.id.textName);
number = itemView.findViewById(R.id.editTextNum);
//date = itemView.findViewById(R.id.textDate);
// init four button
edit = itemView.findViewById(R.id.buttonEdit)
}

Add values to ArrayList from different activity

I'm trying to create an app like shopping cart
Using this to access my database http://www.tutecentral.com/restful-api-for-android-part-2/
And i'm stuck at adding products to cart, so far I understand that the selected products go to arraylist in a few tutorials. In the code below I have two Activities, the MaterialView (this shows the details of the materials and has the option to add to cart), and the MaterialCart (shows the list of selected products.)
this is the block of code in MaterialView to send the values to MaterialCart
ButtonAdd.setOnClickListener(new View.OnClickListener(){
public void onClick (View view){
Intent i=new Intent(MaterialView.this, MaterialCart.class);
i.putExtra("mID", mid);
i.putExtra("name", Name.getText().toString());
i.putExtra("qty", Qty.getText().toString());
i.putExtra("price", Price.getText().toString());
i.putExtra("stock", Stock.getText().toString());
i.putExtra("rqQty", RqQty.getText().toString());
startActivity(i);
Toast.makeText(MaterialView.this, "Added Succesfully.", Toast.LENGTH_LONG).show();
}
} );
I have used Intent to pass the values (I'm pretty sure this method is wrong, I also tried calling the MaterialCart class itself to access the arrayList so I can add values and it didn't work)
This is the block of codes in my MaterialCart to receive the values
public class MaterialCart extends Activity {
final ArrayList<PropertyCartTable> materialProperties = new ArrayList<>();
#SuppressLint("LongLogTag")
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_material_cart);
Intent i = new Intent();
Bundle extras = getIntent().getExtras();
try{
String Name = extras.getString("name");
String Qty = extras.getString("qty");
String Price = extras.getString("price");
String Stock = extras.getString("stock");
String RqQty = extras.getString("rqQty");
String ID = extras.getString("mID");
Log.d("EXTRAS:", Name + " " + Qty + " " + ID);
materialProperties.add(new PropertyCartTable( ID,Name,Qty,Price,Stock,RqQty));
getIntent().removeExtra("Name");
getIntent().removeExtra("Qty");
getIntent().removeExtra("Price");
getIntent().removeExtra("Stock");
getIntent().removeExtra("RqQty");
getIntent().removeExtra("MID");
}
catch (Exception h){
Log.d("Exception!",h.toString());
}
// materialProperties.add(array);
Log.d("MaterialView.Cart isEmpty", String.valueOf(materialProperties.isEmpty()));
if(materialProperties.isEmpty()) {
Toast.makeText(this, "You have no materials to request.", Toast.LENGTH_LONG).show();
i = new Intent(MaterialCart.this, ProductDetails.class);
startActivity(i);
}else{
ArrayAdapter<PropertyCartTable> adapter = new propertyArrayAdapter(this, 0, materialProperties);
ListView listView = (ListView) findViewById(R.id.lv_materialcart);
listView.setAdapter(adapter);
}
}
The codes work for receiving the values, but when I go back to the materialView (or choose another product) the ArrayList doesn't append the values.
What I'm trying to achieve here is to add the values from the MaterialView (even if the user adds many prodducts) to MaterialCart's ArrayList.

You can let your Application contain the data:
public class MyApp extends Application {
private static List<String> data = new ArrayList<>();
public static void addItem(String item) {
data.add(item);
}
public static List<String> getData() {
return data;
}
}
And when button is clicked:
ButtonAdd.setOnClickListener(new View.OnClickListener(){
public void onClick (View view){
MyApp.addItem(your item);
Intent i=new Intent(MaterialView.this, MaterialCart.class);
startActivity(i);
}
} );
And in MaterialCart.class:
List<String> data = MyApp.getData();
But remember:data will be clear when app is closed.And if you want save it locally,you need to use SharedPreferences

My getter returns a wrong value

I'm programming an Android application and I got a little problem. I'm trying get a value from the Class A in the Class B but it doesn't return the correct value.
Here's my code to better understand (Sorry for my poor english)!
Class A
package com.androidhive.androidlistview;
//import
public class AndroidListViewActivity extends ListActivity {
int day;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// storing string resources into Array
String[] adobe_products = getResources().getStringArray(R.array.adobe_products);
// Binding Array to ListAdapter
this.setListAdapter(new ArrayAdapter<String>(this, R.layout.list_item, R.id.label, adobe_products));
ListView lv = getListView();
// listening to single list item on click
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// selected item
String product = ((TextView) view).getText().toString();
// Launching new Activity on selecting single List Item
Intent i = new Intent(getApplicationContext(), SingleListItem.class);
day = Integer.parseInt(product.replaceAll("[^\\d.]", ""));
System.out.println(day);
//prints 1 When I click on the first list item, 2 When I click on the second, ...
startActivity(i);
// sending data to new activity
i.putExtra("product", product);
}
});
}
public int getDay() {
return day;
}
}
Class B
package com.androidhive.androidlistview;
//import
#SuppressLint({ "NewApi", "HandlerLeak" })
public class SingleListItem extends Activity {
AndroidListViewActivity alva = new AndroidListViewActivity();
int day;
String url;
String code;
//others variables
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Graphic
new NetworkOperation().execute();
}
class NetworkOperation extends AsyncTask<Void, Void, String> {
protected String doInBackground(Void... params) {
Document doc;
try {
day = alva.getDay();
System.out.println(day);
//prints 0
url = "http://www.planetehockey.com/calendrier.php?saison=45&div=9&club=&journee=" + day + "&jour=&mois=&page=0";
doc = Jsoup.connect(url).get();
//Récupère le texte d'une balise ayant bg_tableau pour class
Elements getId = doc.getElementsByClass("bg_tableau");
code = getId.text();
code = code + "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
handler.sendEmptyMessage(1);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
private Handler handler = new Handler() {
public void handleMessage(android.os.Message msg) {
//other code
}
};
}
Thank's a lot for all your answers it helped me a lot:
How I solved the problem:
Class A
i.putExtra("product", product);
startActivity(i);
and:
Class B
int day = Integer.parseInt(i.getStringExtra("product").replaceAll("[^\\d.]", ""));

In your Class A, you're trying to bundle components AFTER the activity has been called.
put the call function like this..
Intent i = new Intent(getApplicationContext(), SingleListItem.class);
day = Integer.parseInt(product.replaceAll("[^\\d.]", ""));
System.out.println(day);
i.putExtra("product", product);
startActivity(i);
The passes the parameter in a bundle to the called activity.
HTH!

There are two simple solutions for your problem,
1. Pass day values in intent to SingleListItem
Or
2. Make day as a Static member and use it with class Name like,
public static int day; and access it `AndroidListViewActivity.day`
and remove public int getDay() method from AndroidListViewActivity as in both activity it refers a different object of AndroidListViewActivity .

Try doing i.putExtra("product", product); before startActivity(i);

In your Activity A you have written the getter method but not setter method to set the value of day in your code. Just write the setter method also and set the value of day.
public void setDay(int p_day)
{
day=p_day;
}
Make the variable day as static. After setting the day value try to get it in activity B.
I hope this will help you.