如何在Android Studio中使用内存？

public class MyActivity extends AppCompatActivity {
    private static WeakReference<MyActivity> weakRef;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        weakRef = new WeakReference<>(this);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        weakRef.clear();
    }
}

Glide.with(this)
    .load(imageUrl)
    .into(imageView);

public class MySingleton {
    private static MySingleton instance;
    private WeakReference<Context> contextRef;

    private MySingleton(Context context) {
        this.contextRef = new WeakReference<>(context.getApplicationContext());
    }

    public static synchronized MySingleton getInstance(Context context) {
        if (instance == null) {
            instance = new MySingleton(context);
        }
        return instance;
    }

    public Context getContext() {
        return contextRef.get();
    }
}