У меня есть виджет переключателя в строке моего RecyclerView. Я хочу получить доступ к этому виджету для setOnCheckedChangeListener на коммутаторе, поэтому, когда я использую findViewById на коммутаторе в mainActivity, он работает нормально. но когда я выполняю код, приложение вылетает с этой ошибкой.
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.raunak.alarmdemo4/com.raunak.alarmdemo4.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Switch.setOnCheckedChangeListener(android.widget.CompoundButton$OnCheckedChangeListener)' on a null object reference
Но почему NullPointerException ??
Вот фрагмент кода MainActivity:
public class MainActivity extends AppCompatActivity implements AlarmRecyclerViewInterface {
FloatingActionButton mAlarmAddButton;
RecyclerView mRecyclerView;
SQLiteDatabase db;
AlarmsDBhelperClass mAlarmsDBhelperClass;
ArrayList<String> nameArrayList = new ArrayList<>();
ArrayList <String> modeArrayList = new ArrayList<>();
ArrayList<String> repeatArrayList = new ArrayList<>();
ArrayList<String> hoursArrayList = new ArrayList<>();
ArrayList<String> minArrayList = new ArrayList<>();
Switch mSwitch;
AlarmAdapter.AlarmView mAlarmView;
AlarmAdapter alarmAdapter = new AlarmAdapter(hoursArrayList,minArrayList,modeArrayList,repeatArrayList,nameArrayList,this);
ImageView emptyImageView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
//Initializing RecyclerView, DatabaseHelperClass, FAB button, The ON OFF switch & the empty ImageView
mAlarmsDBhelperClass = new AlarmsDBhelperClass(getApplicationContext());
mAlarmAddButton = findViewById(R.id.btnAlarmADD);
mRecyclerView = findViewById(R.id.alarmList);
mSwitch = findViewById(R.id.onoff);
emptyImageView = findViewById(R.id.empty_view);
//DividerItemDecoration class is used for getting a vertical line between rows of RecyclerView
DividerItemDecoration itemDecoration = new DividerItemDecoration(this,DividerItemDecoration.VERTICAL);
mRecyclerView.addItemDecoration(itemDecoration);
//Getting a writable reference of the Database.
db = mAlarmsDBhelperClass.getWritableDatabase();
//Retrieving values from the database and storing them in custom ArrayLists
boolean isDataEmpty = getAlarm(db);
//Checking if our arrayList is empty? if yes then display some empty list text or an image
if (!isDataEmpty){
mRecyclerView.setVisibility(View.GONE);
emptyImageView.setImageResource(R.drawable.no_alarm_black_white);
emptyImageView.setVisibility(View.VISIBLE);
}
else {
mRecyclerView.setVisibility(View.VISIBLE);
emptyImageView.setVisibility(View.GONE);
}
//FAB Event handling
mAlarmAddButton.setImageResource(R.drawable.addalarm);
mAlarmAddButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent mIntent = new Intent(getApplicationContext(), AddAlarm.class);
startActivity(mIntent);
}
});
mSwitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
if(b){
Calendar c = Calendar.getInstance();
c.set(Calendar.HOUR_OF_DAY, Integer.parseInt(hoursArrayList.get(mAlarmView.getAdapterPosition())));
c.set(Calendar.MINUTE, Integer.parseInt(minArrayList.get(mAlarmView.getAdapterPosition())));
c.set(Calendar.SECOND, 0);
startAlarm(c);
Toast.makeText(getApplicationContext(),"Alarm Turned ON !",Toast.LENGTH_SHORT).show();
}else{
cancelAlarm();
Toast.makeText(getApplicationContext(),"Alarm Turned OFF !",Toast.LENGTH_SHORT).show();
}
}
});
//Warping up with the recyclerView
mRecyclerView.setLayoutManager(new LinearLayoutManager(getApplicationContext()));
mRecyclerView.setAdapter(alarmAdapter);
mRecyclerView.setHasFixedSize(true);
}
public boolean getAlarm(SQLiteDatabase db) {
Cursor cursor = db.rawQuery("SELECT * FROM alarms", new String[]{});
boolean rowExists;
if (cursor.moveToFirst()) {
do {
nameArrayList.add(cursor.getString(2));
modeArrayList.add(cursor.getString(3));
repeatArrayList.add(cursor.getString(4));
hoursArrayList.add(Integer.toString(cursor.getInt(5)));
minArrayList.add(Integer.toString(cursor.getInt(6)));
rowExists = true;
} while (cursor.moveToNext());
}else {
rowExists = false;
}
cursor.close();
return rowExists;
}
//RecyclerView's onClick()
@Override
public void onItemClick(int position) {
Toast.makeText(this, "Alarm Clicked !", Toast.LENGTH_SHORT).show();
}
//RecyclerView's onLongClick()
@Override
public void onLongItemClick(int position) {
//Updating the recyclerView
alarmAdapter.notifyItemRemoved(position);
//Deleting the row from the database
db.delete("alarms","alarm_name=?",new String[]{nameArrayList.get(position)});
hoursArrayList.remove(position);
Toast.makeText(this,"Alarm Deleted !", Toast.LENGTH_SHORT).show();
}
public void startAlarm(Calendar c){
//Getting a System service for the alarm to check the current time with the Alarm set time.
AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
//Creating an intent to invoke the onReceive method in the custom receiver class, just to display notifications.
Intent intent = new Intent(getApplicationContext(), AlarmReceiver.class);
//A pending intent is used to execute some work in the future with our applications permissions.
PendingIntent pendingIntent = PendingIntent.getBroadcast(getApplicationContext(),1,intent,0);
//Now RTC_WAKEUP means if the device is Switched off turn it on.
//getTimeInMillis() will get get the time in Milliseconds
//Schedule an alarm to be delivered precisely at the stated time.In my case it's the calendar's getTimeMillis() method. which is providing the correct time in milliseconds.
alarmManager.setExact(AlarmManager.RTC_WAKEUP,c.getTimeInMillis(),pendingIntent);
}
public void cancelAlarm(){
AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(getApplicationContext(),AlarmReceiver.class);
PendingIntent pendingIntent = PendingIntent.getBroadcast(getApplicationContext(),1,intent,0);
//Now i'm cancelling the scheduled alarm using AlarmManager's cancel().
alarmManager.cancel(pendingIntent);
}
}
Мой макет:
<Switch
android:id="@+id/onoff"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="15dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.412" />
Мой адаптер RecyclerView:
public class AlarmAdapter extends RecyclerView.Adapter<AlarmAdapter.AlarmView> {
//Variables for the main recycler view
private ArrayList<String> hoursArrayList;
private ArrayList<String> minArrayList;
private ArrayList<String> modeArrayList;
private ArrayList<String> repeatArrayList;
private ArrayList<String> nameArrayList;
private AlarmRecyclerViewInterface mInterface;
public AlarmAdapter(ArrayList<String> hours,ArrayList<String> mins,ArrayList<String> mode,ArrayList<String> repeat,ArrayList<String> name,AlarmRecyclerViewInterface mInterface){
this.hoursArrayList = hours;
this.minArrayList = mins;
this.modeArrayList = mode;
this.nameArrayList = name;
this.repeatArrayList = repeat;
this.mInterface = mInterface;
}
@NonNull
@Override
public AlarmView onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
LayoutInflater layoutInflater = LayoutInflater.from(parent.getContext());
View view = layoutInflater.inflate(R.layout.alarm_profile,parent,false);
return new AlarmView(view);
}
@Override
public void onBindViewHolder(@NonNull AlarmView holder, int position) {
if(Integer.parseInt(hoursArrayList.get(position)) < 10 ){
holder.hours.setText("0"+hoursArrayList.get(position));
}else {
holder.hours.setText(hoursArrayList.get(position));
}
if (Integer.parseInt(minArrayList.get(position)) < 10){
holder.mins.setText("0"+minArrayList.get(position));
}else {
holder.mins.setText(minArrayList.get(position));
}
holder.repeat.setText(repeatArrayList.get(position));
holder.mode.setText(modeArrayList.get(position));
holder.name.setText(nameArrayList.get(position));
}
@Override
public int getItemCount() {
return hoursArrayList.size();
}
/*ItemTouchHelper.SimpleCallback itemTouchHelperCallback = new ItemTouchHelper.SimpleCallback(0,ItemTouchHelper.RIGHT) {
@Override
public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder target) {
return false;
}
@Override
public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
nameArrayList.remove(viewHolder.getAdapterPosition());
modeArrayList.remove(viewHolder.getAdapterPosition());
repeatArrayList.remove(viewHolder.getAdapterPosition());
hoursArrayList.remove(viewHolder.getAdapterPosition());
minArrayList.remove(viewHolder.getAdapterPosition());
}
};*/
public class AlarmView extends RecyclerView.ViewHolder{
TextView hours,mins,repeat,name,mode;
public AlarmView(@NonNull View itemView) {
super(itemView);
hours = itemView.findViewById(R.id.txtHOUR);
mins = itemView.findViewById(R.id.txtMins);
repeat = itemView.findViewById(R.id.txtRepeatDays);
name = itemView.findViewById(R.id.txtName);
mode = itemView.findViewById(R.id.txtMode);
itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
mInterface.onItemClick(getAdapterPosition());
}
});
itemView.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View view) {
mInterface.onLongItemClick(getAdapterPosition());
return true;
}
});
}
}
}
Спасибо за помощь!