Sending data back to the Main Activity in Android

Question

I have two activities: main activity and child activity.
When I press a button in the main activity, the child activity is launched.

Now I want to send some dat

Answer 1

There are some ways of doing this. 1. by using the startActivityForResult() which is very well explained in the above answers.

2. by creating the static variables in your "Utils" class or any other class of your own. For example i want to pass studentId from ActivityB to ActivityA.First my ActivityA is calling the ActivityB. Then inside ActivityB set the studentId (which is a static field in Utils.class). Like this Utils.STUDENT_ID="1234"; then while comming back to the ActivityA use the studentId which is stored in Utils.STUDENT_ID.

3. by creating a getter and setter method in your Application Class.

like this:

public class MyApplication extends Application {

    private static MyApplication instance = null;
    private String studentId="";

    public static MyApplication getInstance() {
        return instance;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        instance = this;
    }

    public void setStudentId(String studentID){
        this.studentId=studentID;
    }

    public String getStudentId(){
        return this.studentId;
    }
}

so you are done . just set the data inside when u are in ActivityB and after comming back to ActivityA , get the data.

Answer 2

Call the child activity Intent using the startActivityForResult() method call

There is an example of this here: http://developer.android.com/training/notepad/notepad-ex2.html

and in the "Returning a Result from a Screen" of this: http://developer.android.com/guide/faq/commontasks.html#opennewscreen

Answer 3

Another way of achieving the desired result which may be better depending on your situation is to create a listener interface.

By making the parent activity listen to an interface that get triggered by the child activity while passing the required data as a parameter can create a similar set of circumstance

Answer 4

Use sharedPreferences and save your data and access it from anywhere in the application

save date like this

SharedPreferences sharedPreferences = getPreferences(MODE_PRIVATE);
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.putString(key, value);
    editor.commit();

And recieve data like this

SharedPreferences sharedPreferences = getPreferences(MODE_PRIVATE);
    String savedPref = sharedPreferences.getString(key, "");
    mOutputView.setText(savedPref);

Answer 5

There are a couple of ways to achieve what you want, depending on the circumstances.

The most common scenario (which is what yours sounds like) is when a child Activity is used to get user input - such as choosing a contact from a list or entering data in a dialog box. In this case you should use startActivityForResult to launch your child Activity.

This provides a pipeline for sending data back to the main Activity using setResult. The setResult method takes an int result value and an Intent that is passed back to the calling Activity.

Intent resultIntent = new Intent();
// TODO Add extras or a data URI to this intent as appropriate.
resultIntent.putExtra("some_key", "String data"); 
setResult(Activity.RESULT_OK, resultIntent);
finish();

To access the returned data in the calling Activity override onActivityResult. The requestCode corresponds to the integer passed in in the startActivityForResult call, while the resultCode and data Intent are returned from the child Activity.

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
  super.onActivityResult(requestCode, resultCode, data);
  switch(requestCode) {
    case (MY_CHILD_ACTIVITY) : {
      if (resultCode == Activity.RESULT_OK) {
        // TODO Extract the data returned from the child Activity.
        String returnValue = data.getStringExtra("some_key");
      }
      break;
    } 
  }
}

Answer 6

All these answers are explaining the scenario of your second activity needs to be finish after sending the data.

But in case if you don't want to finish the second activity and want to send the data back in to first then for that you can use BroadCastReceiver.

In Second Activity -

Intent intent = new Intent("data");
intent.putExtra("some_data", true);
LocalBroadcastManager.getInstance(this).sendBroadcast(intent);

In First Activity-

private BroadcastReceiver tempReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        // do some action
    }
};

Register the receiver in onCreate()-

 LocalBroadcastManager.getInstance(this).registerReceiver(tempReceiver,new IntentFilter("data"));

Unregister it in onDestroy()