How to return a result (startActivityForResult) from a TabHost Activity?

I have 3 classes in my example: Class A, the main activity. Class A calls a startActivityForResult:

Intent intent = new Intent(this, ClassB.class);
startActivityForResult(intent, "STRING");

Class B, this class is a TabActivity:

Intent intent = new Intent(this, ClassC.class);
tabHost.addTab...

Class C, this class is a regular Activity:

Intent intent = this.getIntent();
intent.putExtra("SOMETHING", "EXTRAS");
this.setResult(RESULT_OK, intent);
finish();

onActivityResult is called in Class A, but the resultCode is RESULT_CANCELED instead of RESULT_OK and the returned intent is null. How do I return something from the Activity inside a TabHost?

I realize that the problem is that my Class C is actually running inside of Class B, and Class B is what is returning the RESULT_CANCELED back to Class A. I just don't know a work around yet.

Solution 1:

Oh, god! After spending several hours and downloading the Android sources, I have finally come to a solution.

If you look at the Activity class, you will see, that finish() method only sends back the result if there is a mParent property set to null. Otherwise the result is lost.

public void finish() {
    if (mParent == null) {
        int resultCode;
        Intent resultData;
        synchronized (this) {
            resultCode = mResultCode;
            resultData = mResultData;
        }
        if (Config.LOGV) Log.v(TAG, "Finishing self: token=" + mToken);
        try {
            if (ActivityManagerNative.getDefault()
                .finishActivity(mToken, resultCode, resultData)) {
                mFinished = true;
            }
        } catch (RemoteException e) {
            // Empty
        }
    } else {
        mParent.finishFromChild(this);
    }
}

So my solution is to set result to the parent activity if present, like that:

Intent data = new Intent();
 [...]
if (getParent() == null) {
    setResult(Activity.RESULT_OK, data);
} else {
    getParent().setResult(Activity.RESULT_OK, data);
}
finish();

I hope that will be helpful if someone looks for this problem workaround again.

Solution 2:

http://tylenoly.wordpress.com/2010/10/27/how-to-finish-activity-with-results/

With a slight modification for "param_result"

/* Start Activity */
public void onClick(View v) {
    Intent intent = new Intent(Intent.ACTION_VIEW);
    intent.setClassName("com.thinoo.ActivityTest", "com.thinoo.ActivityTest.NewActivity");
    startActivityForResult(intent,90);
}
/* Called when the second activity's finished */
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    switch(requestCode) {
    case 90:
        if (resultCode == RESULT_OK) {
            Bundle res = data.getExtras();
            String result = res.getString("param_result");
            Log.d("FIRST", "result:"+result);
        }
        break;
    }
}

private void finishWithResult()
{
    Bundle conData = new Bundle();
    conData.putString("param_result", "Thanks Thanks");
    Intent intent = new Intent();
    intent.putExtras(conData);
    setResult(RESULT_OK, intent);
    finish();
}

Solution 3:

Intent.FLAG_ACTIVITY_FORWARD_RESULT?

If set and this intent is being used to launch a new activity from an existing one, then the reply target of the existing activity will be transfered to the new activity.

Solution 4:

You could implement a onActivityResult in Class B as well and launch Class C using startActivityForResult. Once you get the result in Class B then set the result there (for Class A) based on the result from Class C. I haven't tried this out but I think this should work.

Another thing to look out for is that Activity A should not be a singleInstance activity. For startActivityForResult to work your Class B needs to be a sub activity to Activity A and that is not possible in a single instance activity, the new Activity (Class B) starts in a new task.