Develop Reference

Null object reference exception while calling mediaplayer methods

I am getting this error while calling my player.pause(); method in my application. I am pausing music using ImageButton. I am calling method from song_list class to pause the track. But, following exception occurs:
Attempt to invoke virtual method 'void android.media.MediaPlayer.pause()' on a null object reference
My MainActivity:
public class MusicKom extends AppCompatActivity {
private static String TAG = "PermissionDemo";
public static final int REQUEST_READ_STORAGE = 112;
private ImageButton btplay;
private ImageButton pausemusic;
public void playbutton(int playbuttonid){
btplay=(ImageButton)findViewById(R.id.play);
btplay.setBackgroundResource(playbuttonid);
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_music_kom);
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
// Create an adapter that knows which fragment should be shown on each page
final viewpageadapter adapter = new viewpageadapter(getSupportFragmentManager());
viewPager.setAdapter(adapter);
Button bt1 = (Button)findViewById(R.id.song_list);
Button bt2 = (Button)findViewById(R.id.album_list);
Button bt3 = (Button)findViewById(R.id.artist_list);
pausemusic = (ImageButton)findViewById(R.id.play);
bt1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
viewPager.setCurrentItem(0);
}
});
bt2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
viewPager.setCurrentItem(1);
}
});
bt3.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
viewPager.setCurrentItem(2);
}
});
pausemusic.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
songs_list sl=new songs_list();
sl.pauseplay();
pausemusic.setBackgroundResource(R.drawable.stop);
}
});
}
}
My song_list Fragment:
public class songs_list extends Fragment {
// Adapter that exposes data from a Cursor to a ListView widget.
private MediaCursorAdapter mediaAdapter = null;
public MediaPlayer player;
private String currentFile="";
private boolean isStarted = true;
private TextView selelctedFile = null;
private View v=null;
private String selectedtitem=null;
private int fileposition;
#Override
public View onCreateView(LayoutInflater inflater, final ViewGroup container, Bundle savedInstanceState) {
player = new MediaPlayer();
// Use cursor to get data from external resource
final Cursor cursor = getActivity().getContentResolver().query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, null, null, null, null);
// check Cursor has data or not
if (null != cursor) {
cursor.moveToFirst();
mediaAdapter = new MediaCursorAdapter(getActivity().getApplicationContext(), R.layout.list_layout, cursor);
v=inflater.inflate(R.layout.fragment_songs_list, container, false);
ListView lv = (ListView)v.findViewById(android.R.id.list);
lv.setAdapter(mediaAdapter);
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
selectedtitem = (String) view.getTag();
startPlay(selectedtitem);
}
});
}
return v;
}
private void startPlay(String file) {
player.stop();
player.reset();
try {
player.setDataSource(file);
player.prepare();
player.start();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
((MusicKom) getActivity()).playbutton(R.drawable.play);
}
public void pauseplay(){
Log.i(TAG, "pauseplay: ");
player.pause();
}
}

How can you call another activity method without actually launching the activity. In your case the another activity is not loaded and hence media player object is not created.
please post the whole code to get more information.

You are using a Fragment as a regular java class. Fragment's onCreateView() is not called when you instantiate Fragment. It is only called when you show a fragment with a valid FragmentTranscation. See Fragment Life cycle.
Comment down if you want the fragment to show up when you have to call pauseplay();, I will add the relevant code.
Otherwise, you should be using a regular java class to create and play/pause a media player from anywhere. Something like:
// package com.example.package_name;
import android.media.MediaPlayer;
public class SoundPlayer {
private MediaPlayer mediaPlayer;
// rawSongId is in form of 'R.id.song_name'
public SoundPlayer(Context context, int rawSongId){
mediaPlayer = MediaPlayer.create(context, rawSongId);
}
public SoundPlayer(Context context, String dataSource){
// handle media player with your data source
}
public void start(){
if(mediaPlayer != null) {
mediaPlayer.start();
}
}
public void pause(){
if(mediaPlayer != null) {
mediaPlayer.pause();
}
}
public void stop(){
if(mediaPlayer != null) {
mediaPlayer.stop(); // reset(); ?
}
}
}
Now, instead of
songs_list sl = new songs_list();
sl.pauseplay();
you can,
String dataSource = ""; // generate your dataSource here
// initialize MediaPlayer with dataSource
SoundPlayer soundPlayer = new SoundPlayer(this, dataSource);
// Use its methods
soundPlayer.start();
soundPlayer.pause();
soundPlayer.stop();
please try to use proper camelCase coding conventions. Your pauseplay() should be pausePlay(); or pauseOrPlay().

Custom DialogFragment is not working

I am trying to create a custom dialog using dialogFragment, here I am not be able to display the dialog. The main problem is overriden code is not getting called. Can anyone fix this issue. Here is my code:
BaseDialogFragment.java
public class BaseDialogFragment extends DialogFragment {
private int layoutId;
protected Activity mActivity;
public void setLayoutId(int layoutId){
this.layoutId = layoutId;
}
public BaseDialogFragment(){
}
#Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setStyle(BaseDialogFragment.STYLE_NO_TITLE, R.style.share_dialog);
}
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState){
View v = inflater.inflate(layoutId, container, false);
return v;
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
mActivity = activity;
}
public void initViews(View v){
getDialog().setCanceledOnTouchOutside(true);
}
}
CustomDialog.java:
#SuppressLint("ValidFragment")
public class CustomDialog extends BaseDialogFragment {
private String message;
private btnOkClick okClickListerner;
private TextView simpleMsg;
private WebView termsConditionWeb;
private Button okBtn;
Boolean isNormalDialog = false;
private Typeface fontClanProBold;
private View v;
private Context context;
public interface btnOkClick{
void clicked();
}
public CustomDialog(String message, btnOkClick okClickListerner, Boolean isNormalDialog){
this.message = message;
this.okClickListerner = okClickListerner;
this.isNormalDialog = isNormalDialog;
this.mActivity = null;
setLayoutId(R.layout.activity_custom_dialog);
initViews(v);
}
#Override
public void initViews(View v) {
super.initViews(v);
this.simpleMsg = (TextView) v.findViewById(R.id.simpleMsg);
this.termsConditionWeb= (WebView) v.findViewById(R.id.termsConditionWeb);
this.okBtn = (Button) v.findViewById(R.id.okBtn);
fontClanProBold = Typeface.createFromAsset(context.getAssets(), "fonts/ufonts.com_clanpro-bold.ttf");
Log.e("isNormal", isNormalDialog.toString());
if(isNormalDialog){
this.simpleMsg.setVisibility(View.VISIBLE);
this.simpleMsg.setText(message);
this.simpleMsg.setTypeface(fontClanProBold);
} else {
this.termsConditionWeb.setVisibility(View.VISIBLE);
this.termsConditionWeb.loadData(message, "text/html", "UTF-8");
}
setCancelable(false);
initEvent(v);
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
this.mActivity = activity;
}
private void initEvent(View v){
okBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(okClickListerner != null){
okClickListerner.clicked();
}
dismiss();
}
});
}
public static void ShowDialog(FragmentManager fm, String message, btnOkClick okClickListerner, Boolean isNormalDialog){
CustomDialog dialog = new CustomDialog(message, okClickListerner, isNormalDialog);
dialog.show(fm, "");
}
}
MainActivity.java
inside a onClickListener
CustomDialog.ShowDialog(getSupportFragmentManager(), getResources().getString(R.string.message_register), new CustomDialog.btnOkClick() {
#Override
public void clicked() {
finish();
}
}, isNormalDialog);

It is bad practice to set values inside your Dialog constructor. Instead pass your values as arguments and initialize them on onCreate callback. Furthermore, you shall avoid saving instances of your activity on your fragment, it may lead to memory leaks. Instead I recomend you to create an interface on your CustomDialog or in your BaseDialogFragment that all activitys that uses them must implement. Then you need to implemnt onClickListener interface on your Dialog and inside it you can call mListener.onButtonClickListener(). See the example DialogFragment.
Your CustomDialog would look something like:
public class CustomDialog extends BaseDialogFragment {
private myFragmentInterface mListener;
public static CustomDialog newInstance(String message, Boolean isNormalDialog){
Bundle args = new Bundle();
args.putString(MESSAGE_ARG_KEY, message);
args.putBoolean(TYPE_ARG_KEY, isNormalDialog);
CustomDialog instance = new CustomDialog();
instance.setArguments(args);
}
#override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
message = getArguments().getStirng(MESSAGE_ARG_KEY);
isNormalDialog = getArguments().getBoolean(TYPE_ARG_KEY);
}
#override
public void onAttach(Activity activity){
super.onAttach();
try{
mListener = (myFragmentInterface) activity;
}catch(ClassCastException e){
throw new ClassCastException("activiy must implement myFragmentInterface");
}
}
public void onDetach(){
super.onDetach();
mListener = null;
}
public interface myFragmentInterface{
onButtonClickListener(String... params);
}
}

How to update a textview in a dialog fragment from an activity?

It may be a silly question but I didn't find a good way to update a dialogfragment's textview from an activity in my android app.
What I'd like to do is to update the textview every second with a counter value and once the time elapsed, a Runnable closes the dialog fragment.
The dialog is closed once the time is elapsed, no problem but I cannot update the textview I want.
Here's my code for the dialog:
public class AlertDialog extends DialogFragment {
private String message = null;
private String title = null;
private ImageView imgV = null;
private TextView msgTv = null;
private TextView counterTv = null;
private Button okBtn = null;
private int imageId = 0;
public static int AUTOMATIC_CLOSE = 100001;
private AlertDialogListener mDialogListener;
public void setImage(int i){
imageId = i;
}
public void setContent(String ttl, String msg){
message = msg;
title = ttl;
}
public boolean hasContent(){
return message != null && title != null;
}
public AlertDialog(){
}
public void performClick(){
okBtn.performClick();
}
public void updateField(String text){
counterTv.setText(text);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.dialog, container);
msgTv = (TextView)v.findViewById(R.id.textDialog);
imgV = (ImageView)v.findViewById(R.id.imageDialog);
counterTv = (TextView)v.findViewById(R.id.timeCounterDialog);
if(imageId != 0)
imgV.setImageResource(imageId);
else
imgV.setImageResource(R.drawable.error_icon);
if(hasContent()){
msgTv.setText(message);
getDialog().setTitle(title);
}
else{
getDialog().setTitle("ERROR");
msgTv.setText("An unexcepted error occured");
}
okBtn = (Button)v.findViewById(R.id.validateButton);
okBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(mDialogListener != null){
mDialogListener.onFinishedDialog();
}
}
});
return v;
}
#Override
public void onStart() {
mDialogListener.onStartedDialog();
super.onStart();
}
#Override
public void onAttach(Activity activity) {
mDialogListener = (AlertDialogListener) activity;
super.onAttach(activity);
}
#Override
public void onDetach() {
mDialogListener = null;
super.onDetach();
}
public interface AlertDialogListener{
void onStartedDialog();
void onFinishedDialog();
}
}
And this is how I launch it:
class myActivity extends Activity implements AlertDialogListener{
protected void onCreate(Bundle savedInstanceState){
"""some init stuff"""
button.setOnClickListener(new View.OnClickListener() {
showAlertDialog();
}
}
#Override
public void onStartedDialog() {
AutoCloseRunnable mAutoClose = new AutoCloseRunnable();
mHandler.postDelayed(mAutoClose, 1000);
}
#Override
public void onFinishedDialog() {
this.finish();
}
private void showAlertDialog(){
FragmentManager fm = getFragmentManager();
mAlertDialog = new AlertDialog();
mAlertDialog.setContent("No Connection available", "Please enable your internet connection.");
mAlertDialog.setImage(R.drawable.error_icon);
mAlertDialog.show(fm, "fragment_alert");
}
private void updateAlertDialog(String text){
mAlertDialog.updateField(text);
}
private void autoCloseAlertDialog(){
mAlertDialog.performClick();
}
public class AutoCloseRunnable implements Runnable{
#Override
public void run() {
int closeCpt = 10;
while(closeCpt >= 0){
try {
Thread.sleep(1000);
updateAlertDialog("Will close automatically in " + closeCpt + " seconds.");
closeCpt--;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
autoCloseAlertDialog();
}
}
}
Does anyone know how to proceed?

I solved it, simply use asynctask it's easier to handle UI updates like this.

Call method of interface implements with child fragment From container activity Android

I'm stuck with communication between activity and fragment using interface. I have created activity with child fragment. I wanna do some stuff with continuous thread defined in activity and during that thread when I'm getting some result at that time I wanna trigger to child fragment to do something.
My Container Activity
public class MySpaceActivity extends BaseDrawerActivity {
private OnSetLastSeenListener mListner;
public static Thread mThread = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
super.setHeaders(Const.MY_SPACE);
super.setSubmenus(Const.MY_SPACE,
Utils.getSubmenuList(Const.MY_SPACE, MySpaceActivity.this),
submenuBean);
// super.attachFragment(submenuBean);
}
#Override
public void setHeaderSubMenu(SubmenuBean subMenuBean) {
// txt_submenu.setText(subMenuBean.getSubmenu_name());
this.submenuBean = subMenuBean;
Log.print("::::: setHeaderSubMenu ::::");
super.attachFragment(submenuBean);
}
public void setsubFragment(SubmenuBean subMenuBean) {
this.submenuBean = subMenuBean;
super.attachSubFragment(submenuBean);
}
#Override
public void onBackPressed() {
super.onBackPressed();
popLastFragment();
}
private void popLastFragment() {
if (super.getNumberOfChilds() > 1) {
super.popSubFragment();
} else {
finish();
}
}
#Override
protected Fragment getFragement() {
StudentsFragment fragment = new StudentsFragment(Const.MY_SPACE,
getSubmenubean());
return fragment;
}
public SubmenuBean getSubmenubean() {
return submenuBean;
}
#Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
mThread = new Thread(new CountDownTimer(MySpaceActivity.this));
mThread.start();
}
#Override
protected void onStop() {
// TODO Auto-generated method stub
super.onStop();
if (mThread.isAlive()) {
mThread.interrupt();
mThread = null;
}
}
public void updateLastSeen(){
Log.print("::::::Call Interface::::::");
mListner.updateLastSeen();
}
class CountDownTimer implements Runnable {
private Context mContext;
private JSONObject mJsonObject;
private JSONArray mJsonArray;
public CountDownTimer(Context mContext) {
this.mContext = mContext;
}
// #Override
public void run() {
while (!Thread.currentThread().isInterrupted()) {
try {
HttpChatLastSeen mChat = new HttpChatLastSeen();
mJsonObject = mChat.Http_ChatLastSeen(mContext);
String mResult = mJsonObject.getString("Result");
if (mResult.equalsIgnoreCase(String
.valueOf(Const.RESULT_OK))) {
mJsonArray = mJsonObject.getJSONArray("UserData");
for (int i = 0; i < mJsonArray.length(); i++) {
mJsonObject = mJsonArray.getJSONObject(i);
new DbStudentMasterBll(mContext).update(
"last_seen", mJsonObject
.getString("LastSeen"), Integer
.parseInt(mJsonObject
.getString("UserId")));
}
} else {
Log.print("MY LAST SEEN Response : "
+ mJsonObject.toString());
}
updateLastSeen();
Thread.sleep(15000);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
} catch (Exception e) {
Log.print("ChatLastSeenThread : ", e.getMessage());
}
}
}
}
}
My Child Fragment With Interface :
public class StudentsFragment extends Fragment implements OnSetLastSeenListener{
TextView txt_submenu;
ListView list_students;
SubmenuBean submenuBean;
int Mainmenu;
MySpaceActivity mMySpaceActivity;
ArrayList<DbStudentMasterBean> studentsList;
StudentsAdapter mAdapter = null;
OnSetLastSeenListener mListner;
public StudentsFragment() {
super();
}
public StudentsFragment(int Mainmenu, SubmenuBean submenuBean) {
this.submenuBean = submenuBean;
this.Mainmenu = Mainmenu;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_students, container,
false);
mMySpaceActivity = (MySpaceActivity) getActivity();
txt_submenu = (TextView) view.findViewById(R.id.txt_submenu);
txt_submenu.setText(submenuBean.getSubmenu_name());
txt_submenu.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
mMySpaceActivity.openDrawer();
}
});
list_students = (ListView) view.findViewById(R.id.list_colleagues);
studentsList = new DbStudentMasterBll(getActivity()).getAllRecords();
mAdapter = new StudentsAdapter(getActivity(), studentsList, handler);
list_students.setAdapter(mAdapter);
list_students.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
DbStudentMasterBean bean = (DbStudentMasterBean) parent
.getAdapter().getItem(position);
Message msg = new Message();
msg.what = CHAT;
msg.obj = bean;
handler.sendMessage(msg);
}
});
return view;
}
Handler handler = new Handler() {
public void handleMessage(android.os.Message msg) {
switch (msg.what) {
case CHAT:
submenuBean.setTag(VIEWCHATSTUDENT);
DbStudentMasterBean bean = (DbStudentMasterBean) msg.obj;
mMySpaceActivity.setsubFragment(submenuBean);
break;
}
};
};
#Override
public void updateLastSeen() {
// TODO Auto-generated method stub
Log.print("!!!!!!!!!Refresh Adapter!!!!!!!!!!!");
mAdapter.notifyDataSetChanged();
}
}
My Interface :
public interface OnSetLastSeenListener {
public void updateLastSeen();
}
So I have implemented interface OnSetLastSeenListener with my child fragment StudentsFragment . Now I'm calling method of tht interface updateLastSeen() from my container activity with thread. But it is not getting trigger to child fragment where I have implemented interface. So I don't know whether it is good way to communicate or not? Let me take your help to suggest on this solution or best way to communicate from child fragment to parent activity.
Thanks,

It is better to use interface when you want to communicate something from Fragment to Activity and not vice versa.
In your case, you can directly call the method in Fragment from Activity through fragment object. No need to use interface.
Something like this (For static fragments)
StudentsFragment fragment = (StudentsFragment) getFragmentManager()
.findFragmentById(R.id.fragmentid);
if (fragment != null && fragment.isInLayout()) {
fragment.updateLastSeen();
}
For dynamic fragment you can use the fragment object directly.

The value of the variable has been suddenly set to 0

I'm doing an activity to measure how long it takes a person to do an exercise, but it has a bug that I couldn't resolve yet...
The TrainingFragment shows a list of exercises that the user can click and then my ExerciseActivity is launched and runs until the variable "remainingsSets" is setted to 0.
When I click in the first time at any exercise, everything works fine, the ExerciseActivity works correctly end return to the TrainingFragment. But then, if I try to click in another exercise, the ExerciseActivity is just closed.
In my debug, I could see that the variable "remainingSets" comes with it's right value (remainingSets = getIntent().getIntExtra("remaining_sets", 3)), but when the startButton is clicked, I don't know why the variable "remainingSets" is setted to 0 and then the activity is closed because this condition: if (remainingSets > 0){...}.
Here is my TrainingFragment:
public class TrainingFragment extends Fragment {
private final static int START_EXERCISE = 1;
private Training training;
private String lastItemClicked;
private String[] values;
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
Bundle bundle = getArguments();
if (bundle != null) {
training = bundle.getParcelable("training");
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return (ScrollView) inflater.inflate(R.layout.template_exercises, container, false);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
LinearLayout exercisesContainer = (LinearLayout) getView().findViewById(R.id.exercises);
LayoutInflater inflater = (LayoutInflater) getActivity().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
List<Exercise> exercises = training.getExercises();
values = new String[exercises.size()];
if (savedInstanceState != null) {
values = savedInstanceState.getStringArray("values");
}
for (int i = 0; i < exercises.size(); i++) {
final View exerciseView = inflater.inflate(R.layout.template_exercise, null);
exerciseView.setTag(String.valueOf(i));
TextView remainingSets = (TextView) exerciseView.findViewById(R.id.remaining_sets);
if (savedInstanceState != null) {
remainingSets.setText(values[i]);
} else {
String sets = exercises.get(i).getSets();
remainingSets.setText(sets);
values[i] = sets;
}
exerciseView.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(getActivity(), ExerciseActivity.class);
intent.putExtra("remaining_sets",
Integer.valueOf(((TextView) v.findViewById(R.id.remaining_sets)).getText().toString()));
lastItemClicked = v.getTag().toString();
startActivityForResult(intent, START_EXERCISE);
}
});
exercisesContainer.addView(exerciseView);
}
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putStringArray("values", values);
}
#Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
View view = ((LinearLayout) getView().findViewById(R.id.exercises)).findViewWithTag(lastItemClicked);
if (requestCode == START_EXERCISE) {
if (resultCode == Activity.RESULT_OK) { // the exercise had been
// finished.
((TextView) view.findViewById(R.id.remaining_sets)).setText("0");
view.setClickable(false);
values[Integer.valueOf(lastItemClicked)] = "0";
} else if (resultCode == Activity.RESULT_CANCELED) {
String remainingSets = data.getStringExtra("remaining_sets");
((TextView) view.findViewById(R.id.remaining_sets)).setText(remainingSets);
values[Integer.valueOf(lastItemClicked)] = remainingSets;
}
}
}
}
My ExerciseActivity:
public class ExerciseActivity extends Activity {
private Chronometer chronometer;
private TextView timer;
private Button startButton;
private Button endButton;
private int remainingSets;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_exercise);
ExerciseEvents.addExerciseListener(new PopupExerciseListener());
chronometer = (Chronometer) findViewById(R.id.exercise_doing_timer);
timer = (TextView) findViewById(R.id.timer);
startButton = (Button) findViewById(R.id.start_exercise);
startButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
ExerciseEvents.onExerciseBegin();
}
});
endButton = (Button) findViewById(R.id.end_exercise);
endButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
ExerciseEvents.onExerciseRest();
}
});
}
#Override
public void onBackPressed() {
Intent intent = new Intent();
intent.putExtra("remaining_sets", String.valueOf(remainingSets));
setResult(RESULT_CANCELED, intent);
super.onBackPressed();
}
public class PopupExerciseListener implements ExerciseListener {
public PopupExerciseListener() {
remainingSets = getIntent().getIntExtra("remaining_sets", 3);
}
#Override
public void onExerciseBegin() {
if (remainingSets > 0) {
chronometer.setVisibility(View.VISIBLE);
timer.setVisibility(View.GONE);
chronometer.setBase(SystemClock.elapsedRealtime());
chronometer.start();
startButton.setVisibility(View.GONE);
endButton.setVisibility(View.VISIBLE);
} else {
ExerciseEvents.onExerciseFinish();
}
}
#Override
public void onExerciseFinish() {
setResult(RESULT_OK);
finish();
}
#Override
public void onExerciseRest() {
chronometer.setVisibility(View.GONE);
endButton.setVisibility(View.GONE);
timer.setVisibility(View.VISIBLE);
long restTime = getIntent().getLongExtra("time_to_rest", 60) * 1000;
new CountDownTimer(restTime, 1000) {
#Override
public void onTick(long millisUntilFinished) {
timer.setText(String.valueOf(millisUntilFinished / 1000));
}
#Override
public void onFinish() {
ExerciseEvents.onExerciseBegin();
}
}.start();
remainingSets--;
}
}
}
And my ExerciseEvents:
public class ExerciseEvents {
private static LinkedList<ExerciseListener> mExerciseListeners = new LinkedList<ExerciseListener>();
public static void addExerciseListener(ExerciseListener listener) {
mExerciseListeners.add(listener);
}
public static void removeExerciseListener(String listener) {
mExerciseListeners.remove(listener);
}
public static void onExerciseBegin() {
for (ExerciseListener l : mExerciseListeners) {
l.onExerciseBegin();
}
}
public static void onExerciseRest() {
for (ExerciseListener l : mExerciseListeners) {
l.onExerciseRest();
}
}
public static void onExerciseFinish() {
for (ExerciseListener l : mExerciseListeners) {
l.onExerciseFinish();
}
}
public static interface ExerciseListener {
public void onExerciseBegin();
public void onExerciseRest();
public void onExerciseFinish();
}
}
Could anyone give me any help?

After you updated your code, I see you have a big memory leak in your code:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_exercise);
ExerciseEvents.addExerciseListener(new PopupExerciseListener());
....
}
The call ExerciseEvents.addExerciseListener(new PopupExerciseListener()) adds a new PopupExerciseListener to a static/global list: ExcerciseEvents.mExerciseListeners. Since the class PopupExerciseListener is an inner-class, it implicitly holds a reference to its enclosing ExcerciseActivity. This mean your code is holding on to each instance of ExcerciseActivity forever. Not good.
This may also explain the weird behavior you see. When one of the onExcersizeXXX() methods is called, it will call all ExcerciseListeners in the linked-list, the ones from previous screens and the current one.
Try this in your ExcerciseActivity.java:
....
ExerciseListener mExerciseListener;
....
#Override
protected void onCreate(Bundle savedInstanceState) {
....
....
mExerciseListener = new PopupExerciseListener()
ExerciseEvents.addExerciseListener(mExerciseListener);
....
....
}
#Override
protected void onDestroy() {
ExerciseEvents.removeExerciseListener(mExerciseListener);
super.onDestroy();
}
....
In onDestroy, you deregister your listener, preventing a memory leak and preventing odd multiple callbacks to PopupExerciseListeners that are attached to activities that no longer exist.