meaning of RuntimeException(“Stub!”) in Android

Question

I was surfing in Android code because I wanted to see what is into Activity.finish() method.

I just wanted to have the confirmation that in Activity.finish()

Answer 1

I don't know where you looked, but the code for finish() is this

/**
 * Call this when your activity is done and should be closed.  The
 * ActivityResult is propagated back to whoever launched you via
 * onActivityResult().
 */
public void finish() {
    finish(DONT_FINISH_TASK_WITH_ACTIVITY);
}

which calls the private implementation

/**
 * Finishes the current activity and specifies whether to remove the task associated with this
 * activity.
 */
private void finish(int finishTask) {
    if (mParent == null) {
        int resultCode;
        Intent resultData;
        synchronized (this) {
            resultCode = mResultCode;
            resultData = mResultData;
        }
        if (false) Log.v(TAG, "Finishing self: token=" + mToken);
        try {
            if (resultData != null) {
                resultData.prepareToLeaveProcess(this);
            }
            if (ActivityManagerNative.getDefault()
                    .finishActivity(mToken, resultCode, resultData, finishTask)) {
                mFinished = true;
            }
        } catch (RemoteException e) {
            // Empty
        }
    } else {
        mParent.finishFromChild(this);
    }
}

Important here is ActivityManagerNative.getDefault().finishActivity which you can find at line 3359 in this file https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/app/ActivityManagerNative.java

If you want to dive deeper, you can just follow the trail.