Before you mark this duplicate, I did view solution to other similar question but it isn't working. I am getting this error only the first time I run my app.
I am not sure why is this happening. I am calling MainActivity.adapter.notifyDataSetChanged in the Main2Activity (Edit Text Activity). The app crashes when after installing during pressing the back button in the EditText actitvity i.e. Main2Activity.java.
MainActivity:
public class MainActivity extends AppCompatActivity {
ListView notesListView;
static ArrayList<String> notesArrayList;
static ArrayAdapter<String> adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
notesListView = (ListView) findViewById(R.id.notesListView);
notesArrayList = new ArrayList<String>();
adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, notesArrayList);
notesListView.setAdapter(adapter);
Main2Activity.myDb = new DatabaseOperations(this);
if (Main2Activity.myDb != null) {
notesArrayList.clear();
Cursor result = Main2Activity.myDb.getData();
if (result.getCount() == 0) {
Log.i("Error", "error");
return;
}
while (result.moveToNext()) {
notesArrayList.add(result.getString(result.getColumnIndex("text")));
}
}
//notesArrayList.add("Akhilesh Chobey");
notesListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
Intent intent = new Intent(getApplicationContext(), Main2Activity.class);
intent.putExtra("notePosition", i);
startActivity(intent);
}
});
notesListView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {
return false;
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.add_button) {
notesArrayList.add("");
}
Intent intent = new Intent(getApplicationContext(), Main2Activity.class);
intent.putExtra("notePosition", notesArrayList.size() - 1);
startActivity(intent);
return true;
}
}
Main2Activity (EditText Activity):
public class Main2Activity extends AppCompatActivity implements TextWatcher {
static DatabaseOperations myDb;
EditText editNote;
int position;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
editNote = (EditText) findViewById(R.id.noteEditText);
myDb = new DatabaseOperations(Main2Activity.this);
Intent intent = getIntent();
position = intent.getIntExtra("notePosition", -1);
if(position != -1){
editNote.setText(MainActivity.notesArrayList.get(position));
}
editNote.addTextChangedListener(this);
}
@Override
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
@Override
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
if (myDb != null) {
}
}
@Override
public void afterTextChanged(Editable editable) {
}
@Override
public void onBackPressed(){
myDb.insertData(editNote.getText().toString());
MainActivity.notesArrayList.set(position, editNote.getText().toString());
MainActivity.adapter.notifyDataSetChanged();
this.finish();
}
}
Log:
07-02 18:45:40.402 17500-17500/com.akhileshchobey.mynotes E/MessageQueue-JNI: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ArrayAdapter.notifyDataSetChanged()' on a null object reference at com.akhileshchobey.mynotes.Main2Activity.onBackPressed(Main2Activity.java:70) at android.app.Activity.onKeyUp(Activity.java:2495) at android.view.KeyEvent.dispatch(KeyEvent.java:2695) at android.app.Activity.dispatchKeyEvent(Activity.java:2746) at android.support.v7.app.AppCompatActivity.dispatchKeyEvent(AppCompatActivity.java:533) at android.support.v7.view.WindowCallbackWrapper.dispatchKeyEvent(WindowCallbackWrapper.java:53) at android.support.v7.app.AppCompatDelegateImplBase$AppCompatWindowCallbackBase.dispatchKeyEvent(AppCompatDelegateImplBase.java:254) at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:2221) at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:3918) at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3880) at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3449) at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3502) at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3468) at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3578) at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3476) at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3635) at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3449) at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3502) at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3468) at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3476) at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3449) at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3502) at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3468) at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3611) at android.view.ViewRootImpl$ImeInputStage.onFinishedInputEvent(ViewRootImpl.java:3772) at android.view.inputmethod.InputMethodManager$PendingEvent.run(InputMethodManager.java:2244) at android.view.inputmethod.InputMethodManager.invokeFinishedInputEventCallback(InputMethodManager.java:1885) at android.view.inputmethod.InputMethodManager.finishedInputEvent(InputMethodManager.java:1876) at android.view.inputmethod.InputMethodManager$ImeInputEventSender.onInputEventFinished(InputMethodManager.java:2221) at android.view.InputEventSender.dispatchInputEventFinished(InputEventSender.java:141) at android.os.MessageQueue.nativePollOnce(Native Method) at android.os.MessageQueue.next(MessageQueue.java:143) at android.os.Looper.loop(Looper.java:122) at android.app.ActivityThread.main(ActivityThread.java:5264) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:900) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:695)
