Question

我在我的主课程中运行以下代码，只是为了让计数器倒数到圣诞节前的天，小时，分钟和秒。从我所看到的，我认为我的代码是正确的（虽然，因为它抛出异常，它可能不是）。谁能看到错误是什么？

final TextView mTextField = new TextView(this);

    Calendar xmas = Calendar.getInstance();
    Calendar now = Calendar.getInstance();

    xmas.set(2011, 12, 25);

    long milliseconds1 = now.getTimeInMillis();
    long milliseconds2 = xmas.getTimeInMillis();
    long diff = milliseconds2 - milliseconds1;
    final long diffSeconds = diff / 1000;
    final long diffMinutes = diff / (60 * 1000);
    final long diffHours = diff / (60 * 60 * 1000);
    final long diffDays = diff / (24 * 60 * 60 * 1000);

    int delay = 1000; // delay for 1 sec.
    int period = 1000; // repeat every sec.

    Timer timer = new Timer();
    timer.scheduleAtFixedRate(new TimerTask()
        {
            public void run()
            {
                mTextField.setText("Days : " + diffDays + " Hours : "  + diffHours + " Minutes : " + diffMinutes + " Seconds : " +diffSeconds);
            }
        }, delay, period);
     setContentView(mTextField);

堆栈跟踪如下......

   10-29 17:27:19.258: ERROR/AndroidRuntime(471): FATAL EXCEPTION: Timer-0
10-29 17:27:19.258: ERROR/AndroidRuntime(471): android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
10-29 17:27:19.258: ERROR/AndroidRuntime(471):     at android.view.ViewRoot.checkThread(ViewRoot.java:2932)
10-29 17:27:19.258: ERROR/AndroidRuntime(471):     at android.view.ViewRoot.requestLayout(ViewRoot.java:629)
10-29 17:27:19.258: ERROR/AndroidRuntime(471):     at android.view.View.requestLayout(View.java:8267)
10-29 17:27:19.258: ERROR/AndroidRuntime(471):     at android.view.View.requestLayout(View.java:8267)
10-29 17:27:19.258: ERROR/AndroidRuntime(471):     at android.view.View.requestLayout(View.java:8267)
10-29 17:27:19.258: ERROR/AndroidRuntime(471):     at android.view.View.requestLayout(View.java:8267)
10-29 17:27:19.258: ERROR/AndroidRuntime(471):     at android.widget.TextView.checkForRelayout(TextView.java:5514)
10-29 17:27:19.258: ERROR/AndroidRuntime(471):     at android.widget.TextView.setText(TextView.java:2724)
10-29 17:27:19.258: ERROR/AndroidRuntime(471):     at android.widget.TextView.setText(TextView.java:2592)
10-29 17:27:19.258: ERROR/AndroidRuntime(471):     at android.widget.TextView.setText(TextView.java:2567)
10-29 17:27:19.258: ERROR/AndroidRuntime(471):     at com.android.sleeps.SleepstosantaActivity$1.run(SleepstosantaActivity.java:44)
10-29 17:27:19.258: ERROR/AndroidRuntime(471):     at java.util.Timer$TimerImpl.run(Timer.java:284)

第44行是mTextField.setText（“Days：”+ diffDays +“Hours：”+ diffHours +“Minutes：”+ diffMinutes +“Seconds：”+ diffSeconds）;

Answer 1

尝试使用处理程序而不是计时器，从日志中看，问题是您无法从timerTask更改UI。

http://developer.android.com/reference/android/os/Handler.html

这里有一些很好的例子：

How to run a Runnable thread in Android?

使用postDelayed在操作之间提供延迟。

你的逻辑有缺陷，看起来应该更像这样：

diff = diff /1000;
final long diffSeconds = diff % 60;
diff = diff / 60;
final long diffMinutes = diff % 60;
...

我没有对此进行测试，但应该可以使用。

Answer 2

您无法与线程中的视图进行交互。 Timer基本上是一个Thread。你必须在这里使用一个带有计时器的处理程序。

Android异常但没有明显错误

2 个答案: