Java（Android Studio） - 无法使用LocalBroadcastManager.getInstance（this）

Question

Fairly new to both Java and Android Studio, most of my code is from tutorials and as such I may not fully understand it, although I am trying to make sure I have some level of understanding of what I am coding.

So I am trying to use the a DatePicker Fragment in order to pick a date and then set a text box to the chosen date. In order to send the string of chosen date to the MainActivity I am trying to use LocalBroadCastManager, using tutorials I have created a broadcast receiver in MainActivity and I am trying to send the broadcast from my fragment however the line

LocalBroadcastManager.getInstance(this).sendBroadcast(intent);

in my Fragment class is underlined with the error

"Error:(51, 30) error: method getInstance in class LocalBroadcastManager cannot be applied to given types; required: Context found: CalendarDatePickerFragment reason: actual argument CalendarDatePickerFragment cannot be converted to Context by method invocation conversion"

I have tried replacing the "this" with a few other things, such as "Context", however they all give me errors. Here is all of my code minus the imports:

MainActivity:

public class MainActivity extends ActionBarActivity implements               
View.OnClickListener {

TextView mainTextView;
Button mainButton;
EditText inputbox;
static String DateInput;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    mainTextView = (TextView) findViewById(R.id.main_textview);
    mainTextView.setText("Set in Java!");
    mainButton = (Button) findViewById(R.id.TimeInpButton);
    mainButton.setOnClickListener(this);
    inputbox = (EditText) findViewById(R.id.inputBox);
    // Register to receive messages. We are registering an observer (mMessageReceiver) to receive Intents with actions named "custom-event-name".
    LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver,
            new IntentFilter("set-date"));
}

private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        // Get extra data included in the Intent
        String setdate = intent.getStringExtra("input-date");
        Log.d("receiver", "Got message: " + setdate);
        inputbox.setText(setdate);
    }
};

@Override
protected void onDestroy() {
    // Unregister since the activity is about to be closed.
    LocalBroadcastManager.getInstance(this).unregisterReceiver(mMessageReceiver);
    super.onDestroy();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}


@Override
public void onClick(View v) {
    DialogFragment DatePickerFrag = new CalendarDatePickerFragment();
    DatePickerFrag.show(getSupportFragmentManager(), "datePicker");


}
}

CalendarDatePickerFragment:

public class CalendarDatePickerFragment extends DialogFragment implements 
DatePickerDialog.OnDateSetListener {



@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {

    final Calendar calendar = Calendar.getInstance();
    int yy = calendar.get(Calendar.YEAR);
    int mm = calendar.get(Calendar.MONTH);
    int dd = calendar.get(Calendar.DAY_OF_MONTH);
    return new DatePickerDialog(getActivity(), this, yy, mm, dd);
}

public void onDateSet(DatePicker view, int yy, int mm, int dd) {
    String compileddate = (dd+" "+mm+" "+yy);
    Log.d("sender", "Broadcasting message");
    Intent intent = new Intent("set-date");
    // You can also include some extra data.
    intent.putExtra("input-date", compileddate);
    LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
}

}

Sorry if I have overcomplicated a very simple question, I felt that it was possible I might be doing something wrong on a larger scale so I thought it would be good to make it clear what I was trying to acheive.

Thank you for any help you can provide.

Answer 1

Error:(51, 30) error: method getInstance in class LocalBroadcastManager cannot be applied to given types; required: Context found: CalendarDatePickerFragment reason: actual argument CalendarDatePickerFragment cannot be converted to Context by method invocation conversion

yes, that's correct. Fragment does not inherit from Context , while Activity does. That's the reason why you can use this in the Activity but not in the DialogFragment subclass. Use getActivity() , in your DialogFragment subclass

LocalBroadcastManager.getInstance(getActivity()).sendBroadcast(intent);