WeekReferenceTest

WeakReferenceSample.java

public class WeakReferenceSample {
    public WeakReferenceSample(Listener listenerWeakReference) {
        this.listenerWeakReference = new WeakReference<>(listenerWeakReference);
    }

    interface Listener {
        void onDone();
    }

    private final WeakReference<Listener> listenerWeakReference;

    void perform() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                final Listener listener = listenerWeakReference.get();
                try {
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                if (listener != null) {
                    listener.onDone();
                }
            }
        }).start();
    }
}

WeakSampleActivity.java

public class WeakSampleActivity extends Activity implements WeakReferenceSample.Listener {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        WeakReferenceSample weakReferenceSample1 = new WeakReferenceSample(this);
        weakReferenceSample1.perform();

        WeakReferenceSample weakReferenceSample2 = new WeakReferenceSample(new WeakReferenceSample.Listener() {
            @Override
            public void onDone() {
                Log.d("WeakSample","Done test 2");
            }
        });
        weakReferenceSample2.perform();
    }

    @Override
    public void onDone() {
        Log.d("WeakSample","Done test 1");
    }
}