Develop Reference

Java.lang.NullPointerException at getapplicationContext() Android

I'm getting NPE when I try to instantiate a class, I already tried using NameOftheClass.this, getApplicationContext(), getApplication(). None of those is working, here is the log:
java.lang.NullPointerException
at br.com.FragmentClientes.<init>(FragmentClientes.java:87)
line 87 is: mRepositorio = new Repositorio(FragmentClientes.this);
And here is the snippet:
public class FragmentClientes extends ActionBarActivity {
private boolean searchCheck;
private List<ClienteModel> clientes = new ArrayList<ClienteModel>();
private ProgressBar progressBar;
private ListView lv;
private ClientViewAdapter ad;
private ClientViewAdapter ads;
private SearchView searchView;
private LinearLayout footerLinearLayout;
private boolean shouldExecuteOnResume;
private Repositorio mRepositorio;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// TODO Auto-generated method stub
setContentView(R.layout.fragment_cliente);
getActionBar().setDisplayHomeAsUpEnabled(true);
getActionBar().setHomeButtonEnabled(true);
SecurePreferences mSessao = new SecurePreferences(FragmentClientes.this, "sessao");
mSessao.put("menuAtual", "Clientes");
lv = (ListView) findViewById(R.id.listaClientes);
}
public FragmentClientes(Integer idViagem) {
clientes = new ArrayList<ClienteModel>();
try {
mRepositorio = new Repositorio(FragmentClientes.this);
List lista = mRepositorio.getClientesViagem(idViagem);
clientes = lista;
ad = new ClientViewAdapter(FragmentClientes.this, this, clientes);
lv.setVerticalFadingEdgeEnabled(true);
lv.setVerticalScrollBarEnabled(true);
lv.setAdapter(ad);
} catch (Exception e) {
e.printStackTrace();
}
}
}

Do not use an activity context inside its constructor, it will now work. Please put all the code from the constructor into a method and call it inside the `onCreate method like this:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// TODO Auto-generated method stub
setContentView(R.layout.fragment_cliente);
getActionBar().setDisplayHomeAsUpEnabled(true);
getActionBar().setHomeButtonEnabled(true);
SecurePreferences mSessao = new SecurePreferences(FragmentClientes.this, "sessao");
mSessao.put("menuAtual", "Clientes");
Integer idViagem = getIntent().getIntExtra(TAG, -1);
init(idViagem);
}
public void init(Integer mId) {
clientes = new ArrayList<ClienteModel>();
try {
mRepositorio = new Repositorio(FragmentClientes.this);
List lista = mRepositorio.getClientesViagem(mId);
clientes = lista;
ad = new ClientViewAdapter(FragmentClientes.this, this, clientes);
lv.setVerticalFadingEdgeEnabled(true);
lv.setVerticalScrollBarEnabled(true);
lv.setAdapter(ad);
} catch (Exception e) {
e.printStackTrace();
}
}
Also, you will need to find another way of passing the integer parameter.
For this, use Intent.putExtra(TAG, idViagem) on the intent which starts the activity and then retrieve the value in the constructor with getIntent().getIntExtra(TAG, -1)
For example if you're starting FragmentClientes activity from another activity:
Intent intent = new Intent(this, FragmentClientes.class);
intent.putExtra("idViagem", int_value_of_id_that_you_passed_through_constructor);
startActivity(intent);

Dont create Parameteriged Activity Constructor
just init your data in Activity Call back methods like onCreate(),onResume()
Start your Activity Using Intent
For more read Activity doc Activity Documnetation

FragmentClientes is an Activity. You should not define a custom counstructor, since the method onCreate behaves as constructor and will be called automatically by the system.
so put you code into onCreate method.
Important: you should never, i mean realy never call new FragmentClientes(1);

It might be because yout ListView is not properly instantiated
private ListView lv;
You never asign (in the code you provided) any instantiation for the object.

AsyncTask onPostExecute UI Changes

It is always the little things that stump me for hours.
I have an onPostExecute method from an AsyncTask class that looks like so:
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
showColumnCounts();
dataDownloadCompleteToast();
}
The toast works just fine. However, my showColumnCounts() method refuses to work. It works just fine on the main thread. I use it during onCreate() just not here. I thought the onPostExecute ran on the UI thread?
Here is my showColumnCounts() method if it is relevant.
public void showColumnCounts() {
TextView totalView = (TextView) findViewById(R.id.totalColumn2);
TextView ignoredView = (TextView) findViewById(R.id.ignoredColumn2);
TextView rView = (TextView) findViewById(R.id.rColumn2);
Cursor c = myDB.getEmptyRColumn("");
int count = c.getCount();
if (count == 0) {
c.close();
return;
}
String unread = String.valueOf(count);
String total = getTotalCount();
int tTotal = Integer.parseInt(total);
int r = tTotal - count;
String read = String.valueOf(r);
totalView.setText(total);
ignoredView.setText(unread);
rView.setText(read);
c.close();
}
I've been fiddling with it for a while now assuming the answer should be obvious but I'm calling uncle. Can't figure it.
Edit***** 6/30
I THINK I've found my problem. In my background thread I am using a parse.com method "query.findInBackground" which I assume is starting a third thread? I'm trying to update this to "query.find" and I'm hoping that will fix.

First of all you should move all your TextView declarations inside your onCreate method
if you want to change or perform some UI operation, if you want to perform some non UI based operations while the thread is running then do that in doInBackground() method

You should move …setText(...) lines into
runOnUiThread(new Runnable(){
void run(){
// UI stuff
});

You need to tell where is your async class located and the showColumnCounts() function located.
If they both where in different class then you should create a context to call the function from the async class.
Take this as example and try.
Example:
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
setContentView(R.layout.main);
new AsyncClass(this);
super.onCreate(savedInstanceState);
}
public void showColumnCounts() {
TextView totalView = (TextView) findViewById(R.id.totalColumn2);
TextView ignoredView = (TextView) findViewById(R.id.ignoredColumn2);
TextView rView = (TextView) findViewById(R.id.rColumn2);
Cursor c = myDB.getEmptyRColumn("");
int count = c.getCount();
if (count == 0) {
c.close();
return;
}
String unread = String.valueOf(count);
String total = getTotalCount();
int tTotal = Integer.parseInt(total);
int r = tTotal - count;
String read = String.valueOf(r);
totalView.setText(total);
ignoredView.setText(unread);
rView.setText(read);
c.close();
}
public class AsyncClass extends AsyncTask<String, Void, Boolean> {
private Activity activity;
public AsyncClass(Activity main_activity) {
this.activity = main_activity;
}
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
activity.showColumnCounts();
dataDownloadCompleteToast();
}
}
}

If you want to do some UI change process in background running operation(ASYNC TASK),you write that codes in UI thread. Example:
YourActivity.this.runOnUiThread(
new Runnable()
void run()
{
//UI changes
showColumnCounts();
});

Passing a TextView or TextView Array to a function in Android

I'm a rookie programmer, and I'm trying to setup a function to pass a TextView or an array of TextViews to a function, so it can be called at various points in the activity.
public class ScoreboardActivity extends Activity {
...
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_scoreboard);
...
final TextView STATVIEW1A = (TextView) findViewById(R.id.place_stat1a); //Team 1
final TextView STATVIEW1B = (TextView) findViewById(R.id.place_stat1b);
final TextView STATVIEW1C = (TextView) findViewById(R.id.place_stat1c);
final TextView STATVIEW1D = (TextView) findViewById(R.id.place_stat1d);
final TextView STATVIEW2A = (TextView) findViewById(R.id.place_stat2a); //Team 2
final TextView STATVIEW2B = (TextView) findViewById(R.id.place_stat2b);
final TextView STATVIEW2C = (TextView) findViewById(R.id.place_stat2c);
final TextView STATVIEW2D = (TextView) findViewById(R.id.place_stat2d);
//final TextView[] STATVIEW = {STATVIEW1A,STATVIEW1B,STATVIEW1C,STATVIEW1D,
// STATVIEW2A,STATVIEW2B,STATVIEW2C,STATVIEW2D};
...
postStats();
... or
postStats(STATVIEW[]);
I want to have a routine to post the (8) TextViews on my activity_scoreobard layout. I have tried just referencing the STATVIEW1A in the function:
public void postStats () {
STATVIEW1AX.setText("#dumps: " + Integer.toString(DUMP1[GAME_NO]));
}
I have also tried referencing each of the TextViews from passing an array of TextViews in the function:
public void postStats (TextView[] VIEWSTAT) {
VIEWSTAT[6].setText("#dumps: "+ Integer.toString(DUMP2[GAME_NO]));
}
While both don't show errors in Eclipse, the program does not like either situation.

Generally it's not a good idea to pass them to function...
but if you want you can try something like this...
TextView[] STATVIEW = new TextView[SIZE];
then to initialize
STATVIEW[0] = (TextView) findViewById(R.id.place_stat1a); //Team 1
STATVIEW[1] = (TextView) findViewById(R.id.place_stat1b);
......
then pass your Array
postStats(STATVIEW);
Alternative would be
create a method and pass the values and set them to TextViews
something like this
public void fillData(String[] data)
{
for (int i=0;i<STATVIEW.length;i++)
{
STATVIEW[i].setText(data[i]);
}
}

It is better to use an array of WeakReference objects to hold the references to your Text views and initialize this array in the OnCreate method of your activity, using this method everytime that system destroy your activity the references to the items can be garbage collected automatically and you won't cause memory leaks. As far as i know the standard way for holding a reference to an ephemeral object like the activity itself or a views on it is to use WeakReference objects.
For understanding what a WeakReference is read the following article on Wikipedia:
http://en.wikipedia.org/wiki/Weak_reference
Also read this page:
https://developer.android.com/reference/java/lang/ref/WeakReference.html

Instead of Overloading postStats() function you can try using postStats(TextView... VIEWSTAT). In this function you can check the number of arguments by VIEWSTAT.length.

ArrayList<TextView> tmpArrayList = new ArrayList<TextView>();
for(int y=0; y<10; y++)
{
tmpArrayList.add(getTextView(txtBoxCount++));
}
this.postStats(tmpArrayList);
private TextView getTextView(int i)
{
int id=0;
try {
id = R.id.class.getField("textview" + i).getInt(0);
}
catch (IllegalArgumentException e) {
e.printStackTrace();
}
catch (SecurityException e) {
e.printStackTrace();
}
catch(IllegalAccessException e) {
e.printStackTrace();
}
catch (NoSuchFieldException e) {
e.printStackTrace();
}
textview = (TextView)findViewById(id);
textview.setTag("0");
return textview;
}
public void postStats (ArrayList<TextView> viewstat) {
//do some work here
}

Cannot call View in Asynctask Android, java

I am trying to call the view from another class in my Asynctask class but it doesn't seem to be working.
Here is my AsyncTack
private class parseSite extends AsyncTask<String, Void, List<Integer>> {
protected List<Integer> doInBackground(String... arg) {
List<Integer> output = new ArrayList<Integer>();
try {
htmlHelper hh = new htmlHelper(new URL(arg[0]));
output = hh.htmlHelper(arg[0]);
} catch (Exception e) {
System.out.println("Error");
}
return output;
}
protected void onPostExecute(List<Integer> exe) {
graph salesView = new graph();
View chartView = salesView.getView(this);
chartView.setLayoutParams(new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.FILL_PARENT,
LinearLayout.LayoutParams.FILL_PARENT, 1f));
LinearLayout layout = (LinearLayout) findViewById(R.id.linearview);
layout.addView(chartView, 0);
}
}
And here is what the activity 'graph' looks like
public class graph {
public View getView(Context context) (...etc.)
I don't understand why it can't call the view.

Assuming you intended graph to extend Context in some way, such as by extending Activity, and that parseSite is defined inside graph, make the following change:
View chartView = salesView.getView(graph.this);
In the original code, this is referring to parseSite which does not extend Context (and does not refer to graph as you probably intend).
As a side note, in typical Java style classes should be named with an upper case letter, i.e. Graph not graph.

I think the problem is that you try to access view from other thread that created it. Usual way is to use runOnUiThread():
(activity).runOnUiThread(new Runnable() {
public void run() {
//call anything to your View objects
}
});

MainActivity.this is not an enclosing class AsyncTask

I'm trying to create an AsyncTask for the 1st time, but I don't have much luck.
My AsyncTask needs to get some information from a server and then add new layouts to the main layout to display this information.
Everything seems to be more or less clear but, the error message "MainActivity is not an enclosing class" is bothering me.
Nobody else seems to have this problem, so I think I miss something very obvious, I just don't know what it is.
Also, I'm not sure if I used the right way to get the context, and because my application doesn't compile so I can't test it.
Your help is much appreciated.
Here is my code:
public class BackgroundWorker extends AsyncTask<Context, String, ArrayList<Card>> {
Context ApplicationContext;
#Override
protected ArrayList<Card> doInBackground(Context... contexts) {
this.ApplicationContext = contexts[0];//Is it this right way to get the context?
SomeClass someClass = new SomeClass();
return someClass.getCards();
}
/**
* Updates the GUI before the operation started
*/
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
/**
* Updates the GUI after operation has been completed
*/
protected void onPostExecute(ArrayList<Card> cards) {
super.onPostExecute(cards);
int counter = 0;
// Amount of "cards" can be different each time
for (Card card : cards) {
//Create new view
LayoutInflater inflater = (LayoutInflater) ApplicationContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
ViewSwitcher view = (ViewSwitcher)inflater.inflate(R.layout.card_layout, null);
ImageButton imageButton = (ImageButton)view.findViewById(R.id.card_button_edit_nickname);
/**
* A lot of irrelevant operations here
*/
// I'm getting the error message below
LinearLayout insertPoint = (LinearLayout)MainActivity.this.findViewById(R.id.main);
insertPoint.addView(view, counter++, new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT));
}
}
}

Eclipse is probably right, and you are trying to access a class (MainActivity) that is inside it's own file from another class that is in its own file (BackgroundWorker) . There is no way to do that - how is one class supposed to know about the other's instance magically? What you can do:
Move the AsyncTask so it is an inner class in MainActivity
Pass off your Activity to the AsyncTask (via its constructor) then acess using activityVariable.findViewById(); (I am using mActivity in the example below) Alternatively, your ApplicationContext (use proper naming convention, the A needs to be lowercase) is actually an instance of MainActivity you're good to go, so do ApplicationContext.findViewById();
Using the Constructor example:
public class BackgroundWorker extends AsyncTask<Context, String, ArrayList<Card>>
{
Context ApplicationContext;
Activity mActivity;
public BackgroundWorker (Activity activity)
{
super();
mActivity = activity;
}
//rest of code...
As for
I'm not sure if I used the right way to get the context
It is fine.

Above example is inner class, here is standalone class...
public class DownloadFileFromURL extends AsyncTask<String, String, String> {
ProgressDialog pd;
String pathFolder = "";
String pathFile = "";
Context ApplicationContext;
Activity mActivity;
public DownloadFileFromURL (Activity activity)
{
super();
mActivity = activity;
}
#Override
protected void onPreExecute() {
super.onPreExecute();
pd = new ProgressDialog(mActivity);
pd.setTitle("Processing...");
pd.setMessage("Please wait.");
pd.setMax(100);
pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
pd.setCancelable(true);
pd.show();
}
#Override
protected String doInBackground(String... f_url) {
int count;
try {
pathFolder = Environment.getExternalStorageDirectory() + "/YourAppDataFolder";
pathFile = pathFolder + "/yourappname.apk";
File futureStudioIconFile = new File(pathFolder);
if(!futureStudioIconFile.exists()){
futureStudioIconFile.mkdirs();
}
URL url = new URL(f_url[0]);
URLConnection connection = url.openConnection();
connection.connect();
// this will be useful so that you can show a tipical 0-100%
// progress bar
int lengthOfFile = connection.getContentLength();
// download the file
InputStream input = new BufferedInputStream(url.openStream());
FileOutputStream output = new FileOutputStream(pathFile);
byte data[] = new byte[1024]; //anybody know what 1024 means ?
long total = 0;
while ((count = input.read(data)) != -1) {
total += count;
// publishing the progress....
// After this onProgressUpdate will be called
publishProgress("" + (int) ((total * 100) / lengthOfFile));
// writing data to file
output.write(data, 0, count);
}
// flushing output
output.flush();
// closing streams
output.close();
input.close();
} catch (Exception e) {
Log.e("Error: ", e.getMessage());
}
return pathFile;
}
protected void onProgressUpdate(String... progress) {
// setting progress percentage
pd.setProgress(Integer.parseInt(progress[0]));
}
#Override
protected void onPostExecute(String file_url) {
if (pd!=null) {
pd.dismiss();
}
StrictMode.VmPolicy.Builder builder = new StrictMode.VmPolicy.Builder();
StrictMode.setVmPolicy(builder.build());
Intent i = new Intent(Intent.ACTION_VIEW);
i.setDataAndType(Uri.fromFile(new File(file_url)), "application/vnd.android.package-archive" );
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
getApplicationContext().startActivity(i);
}
}