pcm2a pcm2a - 4 years ago 148
Android Question

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.

Answer Source

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.

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