每 3 秒显示一次随机图像 - Android Studio答案

【问题标题】：Displaying random image every 3 seconds - Android Studio每 3 秒显示一次随机图像 - Android Studio
【发布时间】：2016-04-18 14:41:13
【问题描述】：

由于某种原因，我似乎无法正确理解这一点。我想要做的是每 3 秒出现三个图像中的任何一个，但由于某种原因，它给了我一个随机图像，然后另一个突然出现并消失。所以总的来说，我希望它每 3 秒生成一张图像，但由于某种原因无法让它工作。下面是我的 VGameView 的代码：

public class VGameView extends View {
private Bitmap parrot;
private Bitmap moneyChest;
private Bitmap bomb;

Random randy;
int savedTime = 0;
long lastTime;
int rndImg;

private String score = "Score: ";
private int scoreCounter = 0;
private Paint scorePaint = new Paint();

public VGameView(Context context) {
    super(context);

    parrot = BitmapFactory.decodeResource(getResources(), R.drawable.parrot);

    moneyChest = BitmapFactory.decodeResource(getResources(), R.drawable.moneychest);

    bomb = BitmapFactory.decodeResource(getResources(), R.drawable.bomb);

    scorePaint.setColor(Color.BLACK);
    scorePaint.setTextSize(50);
}

public boolean onTouchEvent(MotionEvent event) {
    int eventAction = event.getAction();

    int x = (int) event.getX();
    int y = (int) event.getY();

    switch (eventAction) {
        case MotionEvent.ACTION_DOWN:
            break;
    }
    invalidate();
    return true;
}

@Override
protected void onDraw(Canvas canvas) {
    String.valueOf(scoreCounter);
    canvas.drawText(score + scoreCounter, 10, 100, scorePaint);

    long now = System.currentTimeMillis();
    savedTime += now - lastTime;
    lastTime = now;

    if (savedTime > 3000) {
        savedTime = 0;
        Random randy = new Random();
        rndImg = (int) (3 * Math.random()) + 1;
        if (rndImg == 1) {
            canvas.drawBitmap(parrot, 200, 500, null);
        }

        if (rndImg == 2) {
            canvas.drawBitmap(moneyChest, 600, 200, null);
        }

        if (rndImg == 3) {
            canvas.drawBitmap(bomb, 30, 30, null);
        }
    }
}

【问题讨论】：

标签： android android-studio random timer

【解决方案1】：

onDraw() 将在创建视图时调用一次，之后仅在需要重置视图时调用。当您调用 invalidate() 方法时会发生这种情况。

所以，我建议您在创建视图的 Activity 中创建一个线程或处理程序，然后每 3 秒重置一次视图。

VGameView 内部：

@Override
protected void onDraw(Canvas canvas) {
    String.valueOf(scoreCounter);
    canvas.drawText(score + scoreCounter, 10, 100, scorePaint);

        rndImg = (int) (3 * Math.random()) + 1;
        if (rndImg == 1) {
            canvas.drawBitmap(parrot, 200, 500, null);
        }

        if (rndImg == 2) {
            canvas.drawBitmap(moneyChest, 600, 200, null);
        }

        if (rndImg == 3) {
            canvas.drawBitmap(bomb, 30, 30, null);
        }
  }

public void reset(){
    invalidate();
}

内部活动：

Handler mHandler = new Handler();
Runnable changeImage = new Runnable() {
@Override 
public void run() {
      mview.reset();
      mHandler.postDelayed(changeImage, 3000);
    }
};

mHandler.postDelayed(changeImage, 3000);

告诉我这是否有效..

【讨论】：