Java 在Android Studio中设置倒计时

我正在尝试创建一个在左上角有倒计时计时器的游戏

我已经创建了一个文本视图框，并将其命名为“时间”，就我所知，我已经正确设置了计时器，但它没有显示任何内容

我的代码如下：

public class GameView extends SurfaceView implements SurfaceHolder.Callback {

/* Member (state) fields   */
private GameLoopThread gameLoopThread;
private Paint paint; //Reference a paint object 
/** The drawable to use as the background of the animation canvas */
private Bitmap mBackgroundImage;
// For creating the game Sprite
private Sprite sprite;
// For recording the number of hits
private int hitCount;

public GameView(Context context) {
    super(context);
    // Focus must be on GameView so that events can be handled.
    this.setFocusable(true);
    // For intercepting events on the surface.
    this.getHolder().addCallback(this);
    // Background image added
    mBackgroundImage = BitmapFactory.decodeResource(this.getResources(), R.drawable.half_moon);

}
 /* Called immediately after the surface created */
public void surfaceCreated(SurfaceHolder holder) {
    // We can now safely setup the game start the game loop.
    ResetGame();//Set up a new game up - could be called by a 'play again option'
    mBackgroundImage = Bitmap.createScaledBitmap(mBackgroundImage, getWidth(), getHeight(), true);
    gameLoopThread = new GameLoopThread(this.getHolder(), this);
    gameLoopThread.running = true;
    gameLoopThread.start();
}

// For the countdown timer
private long startTime; // Timer to count down from
private final long interval = 1 * 1000; // 1 sec interval
private CountDownTimer countDownTimer; // Reference to the class
private boolean timerRunning = false;
private String displayTime; // To display the time on the screen
private TextView time = (TextView) findViewById(R.id.time);

// Countdown Timer - private class
private class MyCountDownTimer extends CountDownTimer {

    public MyCountDownTimer (long startTime, long interval) {
        super(startTime, interval);
    }
    public void onFinish() {
        displayTime = "Time is up!";
        timerRunning = false;
        countDownTimer.cancel();
    }
    public void onTick (long millisUntilFinished) {
        displayTime = " " + millisUntilFinished / 1000;

    }
}

//To initialise/reset game
private void ResetGame(){
    /* Set paint details */
    paint = new Paint();
    paint.setColor(Color.WHITE); 
    paint.setTextSize(20);
    sprite = new Sprite(this);
    hitCount = 0;
    // Set timer
    startTime = 10; // Start at 10s to count down
    // Create new object - convert startTime to milliseconds
    countDownTimer = new MyCountDownTimer(startTime*1000, interval);
    countDownTimer.start(); // Start the time running
    timerRunning = true;


}


//This class updates and manages the assets prior to drawing - called from the Thread
public void update(){

    sprite.update();

}
/**
 * To draw the game to the screen
 * This is called from Thread, so synchronisation can be done
 */
public void doDraw(Canvas canvas) {
    //Draw all the objects on the canvas
    canvas.drawBitmap(mBackgroundImage, 0, 0, null);
    canvas.drawText("The Game ",15,25, paint);
    sprite.draw(canvas);
}

//To be used if we need to find where screen was touched
public boolean onTouchEvent(MotionEvent event) {
        if (sprite.wasItTouched(event.getX(), event.getY())) {
            // This just renews the sprite for now
            sprite = new Sprite(this);
            hitCount++;
        }
    return true;
}

public void surfaceDestroyed(SurfaceHolder holder) {
    gameLoopThread.running = false;

    // Shut down the game loop thread cleanly.
    boolean retry = true;
    while(retry) {
        try {
            gameLoopThread.join();
            retry = false;
        } catch (InterruptedException e) {}
    }
}

public void getHitCount() {

}

public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

}



}

---

一如既往，非常感谢您的帮助。

在

onTick

方法中，将

displayTime

的值分配到

TextView

用法：

---

time.setText（显示时间）

在

onTick

方法中，将

displayTime

的值分配到

TextView

用法：

---

time.setText（显示时间）
//这是用于16秒倒计时的

 final int sec = 16000;
            countDownTimer = new CountDownTimer(sec, 1000) {

                public void onTick(long millisUntilFinished) {
                    int minute = (int) (millisUntilFinished / 1000) / 60;
                    int second = (int) (millisUntilFinished / 1000) % 60;
                    mTimer.setText(String.format("%02d", minute) + ":" + String.format("%02d", second));
                }

                public void onFinish() {
                                   commonActions.showToast("Successfully Finished");
                }

            };

并通过调用
countDownTimer.start（）启动计时器

如果这不能满足您的需要。请告诉我
//这是一个16秒的倒计时

 final int sec = 16000;
            countDownTimer = new CountDownTimer(sec, 1000) {

                public void onTick(long millisUntilFinished) {
                    int minute = (int) (millisUntilFinished / 1000) / 60;
                    int second = (int) (millisUntilFinished / 1000) % 60;
                    mTimer.setText(String.format("%02d", minute) + ":" + String.format("%02d", second));
                }

                public void onFinish() {
                                   commonActions.showToast("Successfully Finished");
                }

            };

并通过调用
countDownTimer.start（）启动计时器

如果这不符合您的需要。请告诉我您尚未在textView中设置文本。因此，如果您没有在textView中设置文本，它将显示空textView。所以它会显示空文本视图谢谢。但是，添加此行会使应用程序崩溃，并且不会显示时间。我认为这是空指针异常@PhilAdams你能发布logcat日志吗？@PhilAdams更新了答案，请现在查看。Yogesh现在它可能工作了我使用了你更新的答案，它不再崩溃，但仍然不显示timer@PhilAdams请检查我的最新答案。已在onTick上添加日志。所以，你们需要在运行应用程序时检查日志，以确保logcat是否正在打印该日志。若并没有遇到日志，那个么问题在于时间开始感谢。但是，添加此行会使应用程序崩溃，并且不会显示时间。我认为这是空指针异常@PhilAdams你能发布logcat日志吗？@PhilAdams更新了答案，请现在查看。Yogesh现在它可能工作了我使用了你更新的答案，它不再崩溃，但仍然不显示timer@PhilAdams请检查我的最新答案。已在onTick上添加日志。所以，你们需要在运行应用程序时检查日志，以确保logcat是否正在打印该日志。若并没有遇到日志，那个么问题在于开始时间
 final int sec = 16000;
            countDownTimer = new CountDownTimer(sec, 1000) {

                public void onTick(long millisUntilFinished) {
                    int minute = (int) (millisUntilFinished / 1000) / 60;
                    int second = (int) (millisUntilFinished / 1000) % 60;
                    mTimer.setText(String.format("%02d", minute) + ":" + String.format("%02d", second));
                }

                public void onFinish() {
                                   commonActions.showToast("Successfully Finished");
                }

            };