Question

我想以5秒的间隔更改TextView的字符串。所以我写道：

    Intent intent = getIntent();
    int kutisu = Integer.parseInt(intent.getStringExtra("kutisu"));// the number of times
    int max = Integer.parseInt(intent.getStringExtra("max"));
    int speed = 5000;// 5 seconds

    int[] sum=new int[kutisu]; // After finished count, I want to ask for a total  
    int answer = 0;
    for(int i=0;i<=kutisu;i++){
        sum[i]=new java.util.Random().nextInt(max);
        tv.setText(sum[i]); //tv is a TextView
        try {
            Thread.sleep(speed); // stop
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

但是运行它时字符串没有改变。如何每5秒更改一次TextView的字符串？

Answer 1

使用timerTask

public void startTimer() {
//set a new Timer
timer = new Timer();
//initialize the TimerTask's job --> change yourView text data
initializeTimerTask();
//schedule the timer, after the first 5000ms the TimerTask will run every 10000ms
timer.schedule(timerTask, 5000, 10000); //
}

你也可以使用postDelayed，让它以5秒的间隔连续运行，你需要再次在Run方法中将postDelayed作为嵌套召唤

handler.postDelayed(new Runnable() {

  public void run() {
    Log.d("MyActivity", "Ding Ding");
     // --> change yourView text data
    //calling postdelayed again
    handler.postDelayed(this, 5000); //added this line
  }
}, 5000);

Answer 2

复制以下课程

public class UIUpdater {
    // Create a Handler that uses the Main Looper to run in
    private Handler mHandler = new Handler(Looper.getMainLooper());

    private Runnable mStatusChecker;
    private int UPDATE_INTERVAL = 5*1000; //5 seconds

    /**
     * Creates an UIUpdater object, that can be used to
     * perform UIUpdates on a specified time interval.
     *
     * @param uiUpdater A runnable containing the update routine.
     */
    public UIUpdater(final Runnable uiUpdater) {
        mStatusChecker = new Runnable() {
            @Override
            public void run() {
                // Run the passed runnable
                uiUpdater.run();
                // Re-run it after the update interval
                mHandler.postDelayed(this, UPDATE_INTERVAL);
            }
        };
    }

    /**
     * The same as the default constructor, but specifying the
     * intended update interval.
     *
     * @param uiUpdater A runnable containing the update routine.
     * @param interval  The interval over which the routine
     *                  should run (milliseconds).
     */
    public UIUpdater(Runnable uiUpdater, int interval){

        this(uiUpdater);
        UPDATE_INTERVAL = interval;
    }

    /**
     * Starts the periodical update routine (mStatusChecker
     * adds the callback to the handler).
     */
    public synchronized void startUpdates(){
        mStatusChecker.run();
    }

    /**
     * Stops the periodical update routine from running,
     * by removing the callback.
     */
    public synchronized void stopUpdates(){
        mHandler.removeCallbacks(mStatusChecker);
    }
}

请注意，在上面的类变量UPDATE_INTERVAL中确定更新的时间间隔，请根据需要进行更改。

然后在你的活动或片段中

UIUpdater mUIUpdater = new UIUpdater(new Runnable() {
    @Override
    public void run() {
        //do what ever you want to do with your textview 
    }
});

并在onResume

@Override
public void onResume() {
    super.onResume();
    mUIUpdater.startUpdates();
}

并在onPause

@Override
public void onPause() {
    super.onPause();
    mUIUpdater.stopUpdates();

}

Answer 3

   Handler handler = new Handler();
   private Runnable myRunnable=new Runnable(){
    public void run(){
        //Do what you want to your textView here
        handler.postDelayed(this, 5000);      
    }
};

Answer 4

您可以在同一个地方使用2个TextView

private void startFirstFadeOut() {
        Animation animation = new AlphaAnimation(1f, 0f);
        animation.setDuration(ANIMATION_DURATION);
        animation.setAnimationListener(new Animation.AnimationListener() {
            @Override
            public void onAnimationStart(Animation animation) {

            }

            @Override
            public void onAnimationEnd(Animation animation) {
                firstTextView.setVisibility(INVISIBLE);
                startSecondFadeIn();
            }

            @Override
            public void onAnimationRepeat(Animation animation) {

            }
        });
        firstTextView.setAnimation(animation);
        firstTextView.animate();
    }

    private void startSecondFadeIn() {
        Animation animation = new AlphaAnimation(0f, 1f);
        animation.setDuration(ANIMATION_DURATION);
        animation.setAnimationListener(new Animation.AnimationListener() {
            @Override
            public void onAnimationStart(Animation animation) {
                secondTextView.setVisibility(VISIBLE);
            }

            @Override
            public void onAnimationEnd(Animation animation) {
                startSecondFadingOut();
            }

            @Override
            public void onAnimationRepeat(Animation animation) {

            }
        });
        secondTextView.setAnimation(animation);
        secondTextView.animate();
    }

    private void startSecondFadingOut() {
        Animation animation = new AlphaAnimation(1f, 0f);
        animation.setDuration(ANIMATION_DURATION);
        animation.setAnimationListener(new Animation.AnimationListener() {
            @Override
            public void onAnimationStart(Animation animation) {

            }

            @Override
            public void onAnimationEnd(Animation animation) {
                secondTextView.setVisibility(INVISIBLE);
                startFirstFadingIn();
            }

            @Override
            public void onAnimationRepeat(Animation animation) {

            }
        });
        secondTextView.setAnimation(animation);
        secondTextView.animate();
    }

    private void startFirstFadingIn() {
        Animation animation = new AlphaAnimation(0f, 1f);
        animation.setDuration(ANIMATION_DURATION);
        animation.setAnimationListener(new Animation.AnimationListener() {
            @Override
            public void onAnimationStart(Animation animation) {
                firstTextView.setVisibility(VISIBLE);
            }

            @Override
            public void onAnimationEnd(Animation animation) {
                startFirstFadeOut();
            }

            @Override
            public void onAnimationRepeat(Animation animation) {

            }
        });
        firstTextView.setAnimation(animation);
        firstTextView.animate();
    }

只需致电startFirstFadeOut，一切都将自动生效

Answer 5

我使用这种方式：

from itertools import groupby

[next(v) for k,v in groupby(test)]
# [['B', [4, 5, 6]], ['C', [7, 8, 9]]]

enter image description here

我想以5秒的间隔更改TextView的文本

5 个答案: