安卓进度条 : loading with Timer

Question

Update: This post was from when I was learning android with android 2.2, be sure to check if this is compatible with the api level you are working with.

四处寻找如何使用计时器加载进度条，我尝试使用已发布的方法，但总是会出现指针异常，或者测试应用程序会在启动时崩溃。

我的问题是，大声笑有没有人看过任何关于如何做到这一点的教程或示例？我在想我所需要的只是一个 while 循环，但还没有看到在计时器上完成的。我是一个完全的菜鸟，但正在缓慢但肯定地学习

我的计时器

final Timer t = new Timer();
    t.schedule(new TimerTask() {
        public void run() {
            d.dismiss();  //MY DIALOG WINDOW
            t.cancel();
        }
    }, 7000);   

这是我试图开始工作但认为我造成的伤害比用它做得更好

isRunning = false;
    // handler for the background updating
    final Handler handler = new Handler() {
        public void handleMessage(Message msg) {
            total = total - 1;
            String perc = String.valueOf(total).toString();
            a.setText(perc + " SECONDS  until close");
            bar.incrementProgressBy(25);
        }
    };

    super.onStart();
    // reset the bar to the default value of 0
    bar.setProgress(0);
    // create a thread for updating the progress bar
    Thread background = new Thread(new Runnable() {
        public void run() {
            try {
                for (int i = 4; i < 20 && isRunning; i++) {
                    // wait 1000ms between each update
                    Thread.sleep(1000);
                    handler.sendMessage(handler.obtainMessage());
                }
            } catch (Throwable t) {
            }
        }
    });
    isRunning = true;
    // start the background thread
    background.start();

希望有人能够为我阐明这一点，一如既往地对简短的通用问题感到抱歉，只是想了解如何使用计时器加载进度条

再次感谢所有帮助

Answer 1

使用android.os.CountDownTimer

 countDownTimer = new CountDownTimer(length_in_milliseconds,period_in_milliseconds) {
        private boolean warned = false;
        @Override
        public void onTick(long millisUntilFinished_) {
           progressBar.progress = (length_in_milliseconds-millisUntilFinished_)/lenght_in_milliseconds*100.0;
        }

        @Override
        public void onFinish() {
            // do whatever when the bar is full
        }
    }.start();