虽然循环在 Android 上不起作用

Question

我需要以 1 秒的延迟显示数字。如果没有 while 循环，它可以工作，但是一旦我添加了 while 循环，它就会在 while 循环结束后打印值。有人可以在这方面提供帮助。

int state = 0;

int count=0;

@Override

protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);

    button=(Button)findViewById(R.id.b_main);

    textView =(TextView) findViewById(R.id.text_main);

    listView =(ListView) findViewById(R.id.t_main);

    arrayList=new ArrayList<String>();

    button.setOnClickListener(new View.OnClickListener() {

        @Override

        public void onClick(View v) {

            if(state==0){

                state=1;

                try {

                    while(count<10) {

                        textView.setText("Start " + count++);

                        Thread.sleep(1000);

                    }

                } catch (InterruptedException e) {

                    e.printStackTrace();

                }

            }else{

                state=0;

                textView.setText("Stop " + count++);

            }

        }

    });

}

Answer 1

永远不要调用Thread.sleep()UI 线程。您需要将代码放在一个单独的线程中，并使用runOnUiThread以下方法发布结果：if(state==0){&nbsp; &nbsp; state=1;&nbsp; &nbsp; new Thread(new Runnable() {&nbsp; &nbsp; &nbsp; &nbsp; @Override&nbsp; &nbsp; &nbsp; &nbsp; public void run() {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; try {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; while(count<10) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; runOnUiThread(new Runnable() {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; @Override&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; public void run() {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; textView.setText("Start " + count++);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; });&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Thread.sleep(1000);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; count++;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; } catch (InterruptedException e) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;e.printStackTrace();&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }).start();}

Answer 2

不要使用Thread.sleep(). 使用处理程序来强制执行您想要的延迟。&nbsp; &nbsp; final Handler handler = new Handler();&nbsp; &nbsp; final int delay1 = 1000; // adjust as needed&nbsp; &nbsp; &nbsp;handler.postDelayed(new Runnable() {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; public void run() {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; // Code Block 1. Code here will be executed after 1000 millisec&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }, delay1);//&nbsp; Code Block 2. Code here will be executed immediatelly ( before **Code Block 1** )

Answer 3

当您进行与时间相关的操作时，更好的方法是使用CountDownTimer. Thread.sleep()在主线程上使用是不好的，因为当线程休眠时你的 Ui 会卡住这是一个关于如何实现它的示例 CountDownTimerint state = 0, count = 0;&nbsp; &nbsp; TextView textView;&nbsp; &nbsp; CountDownTimer timer;&nbsp; &nbsp; @Override&nbsp; &nbsp; protected void onCreate(@Nullable Bundle savedInstanceState) {&nbsp; &nbsp; &nbsp; &nbsp; super.onCreate(savedInstanceState);&nbsp; &nbsp; &nbsp; &nbsp; setContentView(R.layout.activity_test);&nbsp; &nbsp; &nbsp; &nbsp; button=(Button)findViewById(R.id.b_main);&nbsp; &nbsp; &nbsp; &nbsp; textView =(TextView) findViewById(R.id.text_main);&nbsp; &nbsp; &nbsp; &nbsp; button.setOnClickListener(new View.OnClickListener() {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; @Override&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; public void onClick(View v) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (state == 0) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; state = 1;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; startTimer();&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; } else {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; state = 0;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (timer != null) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; timer.cancel();&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; textView.setText("Stop " + count++);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; });&nbsp; &nbsp; }&nbsp; &nbsp; public void startTimer() {&nbsp; &nbsp; &nbsp; &nbsp; timer = new CountDownTimer(10000, 1000) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; @Override&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; public void onTick(long millisUntilFinished) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; count++;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; textView.setText("Start " + count);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; @Override&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; public void onFinish() {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;//10 sec finished&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; };&nbsp; &nbsp; &nbsp; &nbsp; timer.start();&nbsp; &nbsp; }