无法在android java中解析HandlerHandler.Callback中的构造函数

如何解决无法在android java中解析HandlerHandler.Callback中的构造函数

我正在尝试通过 android java 中的处理程序实现回调，此回调用于生成随机数，用于决定在 imageview 中显示哪个骰子图像，但我的 Java 代码似乎与处理程序有问题我尝试使用的逻辑...

class FullscreenActivity extends AppCompatActivity{
    ImageView dice_picture;  //Reference to dice picture
    Random rng;    //generate random numbers
    SoundPool dice_sound;    //For dice sound playing
    int sound_id;
    android.os.Handler handler;
    Timer timer=new Timer();
    boolean rolling=false;
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
                   super.onCreate(savedInstanceState);
                   setContentView(R.layout.activity_fullscreen);
                      handler=new android.os.Handler(callback);
                                                                 }
 //The constructor in this Handler Callack makes the handler code in OnCreate to be underlined with the error _Cannot resolve Constructor in Handler(Handler.Callback)_
          
 Handler.Callback callback = new Handler.Callback() {
        public boolean handleMessage(Message msg) {
            //Get roll result
            //Remember nextInt returns 0 to 5 for argument of 6
            //hence + 1
            switch(rng.nextInt(6)+1) {
                case 1:
                    dice_picture.setImageResource(R.drawable.one);
                    break;
                case 2:
                    dice_picture.setImageResource(R.drawable.two);
                    break;
                case 3:
                    dice_picture.setImageResource(R.drawable.three);
                    break;
                case 4:
                    dice_picture.setImageResource(R.drawable.four);
                    break;
                case 5:
                    dice_picture.setImageResource(R.drawable.five);
                    break;
                case 6:
                    dice_picture.setImageResource(R.drawable.six);
                    break;
                default:
            }
            rolling=false;  //user can press again
            return true;
        }
    };


  }

这个项目是付费的，非常重要，请帮忙