Android：以特定时间间隔以编程方式打开和关闭屏幕

Question

我需要创建一个应用程序，让屏幕在一段时间内熄灭（例如10秒），然后继续，显示消息2秒钟并再次打开关闭。这一直不断重复，直到点击一个按钮。 （即，我想在单击按钮时停止此活动）。我试图通过改变屏幕亮度来实现这一点。

我的代码是有点像这样：

float dim = 0; 
float bright = 1.0f; 
WindowManager.LayoutParams lp=getWindow().getAttributes(); 
bright = Settings.System.getInt(getContentResolver(), Settings.System.SCREEN_BRIGHTNESS); 
wait(2000); 
lp.screenBrightness = dim; 
wait(10000); 
lp.screenBrightness = bright; 

如果我没看错，这应该能正常运行。但是当我运行它时，它会变暗，然后显示发生错误，强制关闭消息。

任何帮助将不胜感激。

这里是logcat的错误：

02-22 11:12:50.804: D/AndroidRuntime(10871): Shutting down VM 
02-22 11:12:50.804: W/dalvikvm(10871): threadid=1: thread exiting with uncaught exception (group=0x40018578) 
02-22 11:12:50.859: E/AndroidRuntime(10871): FATAL EXCEPTION: main 
02-22 11:12:50.859: E/AndroidRuntime(10871): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.wakelock/com.example.wakelock.WakeLock}:java.lang.IllegalMonitorStateException: object not locked by thread before wait() 
02-22 11:12:50.859: E/AndroidRuntime(10871): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651) 
02-22 11:12:50.859: E/AndroidRuntime(10871): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667) 
02-22 11:12:50.859: E/AndroidRuntime(10871): at android.app.ActivityThread.access$1500(ActivityThread.java:117) 
02-22 11:12:50.859: E/AndroidRuntime(10871): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935) 
02-22 11:12:50.859: E/AndroidRuntime(10871): at android.os.Handler.dispatchMessage(Handler.java:99) 
02-22 11:12:50.859: E/AndroidRuntime(10871): at android.os.Looper.loop(Looper.java:130) 
02-22 11:12:50.859: E/AndroidRuntime(10871): at android.app.ActivityThread.main(ActivityThread.java:3687) 
02-22 11:12:50.859: E/AndroidRuntime(10871): at java.lang.reflect.Method.invokeNative(Native Method) 
02-22 11:12:50.859: E/AndroidRuntime(10871): at java.lang.reflect.Method.invoke(Method.java:507) 
02-22 11:12:50.859: E/AndroidRuntime(10871): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) 
02-22 11:12:50.859: E/AndroidRuntime(10871): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625) 
02-22 11:12:50.859: E/AndroidRuntime(10871): at dalvik.system.NativeStart.main(Native Method) 
02-22 11:12:50.859: E/AndroidRuntime(10871): Caused by: java.lang.IllegalMonitorStateException: object not locked by thread before wait() 
02-22 11:12:50.859: E/AndroidRuntime(10871): at java.lang.Object.wait(Native Method) 
02-22 11:12:50.859: E/AndroidRuntime(10871): at java.lang.Object.wait(Object.java:395) 
02-22 11:12:50.859: E/AndroidRuntime(10871): at com.example.wakelock.WakeLock.onCreate(WakeLock.java:42) 
02-22 11:12:50.859: E/AndroidRuntime(10871): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
02-22 11:12:50.859: E/AndroidRuntime(10871): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615) 
02-22 11:12:50.859: E/AndroidRuntime(10871): ... 11 more 

Answer 1

我使用的处理程序解决了这个问题。对于任何未来的参考，这里是代码。

float dim = 0.004f; // if you set this 0, it wont work. 0.004 is the least value 
float bright = 1.0f; 
Handler mHandler = new Handler(); 

    mHandler.post(new Runnable() { 

         @Override 
         public void run() { 

          lp.screenBrightness= bright; 
          getWindow().setAttributes(lp);        
          final Handler handler = new Handler(); 
          Timer t = new Timer();        
          t.schedule(new TimerTask() { 
            public void run() { 
              handler.post(new Runnable() { 
                public void run() { 
                lp.screenBrightness=dim; 
                getWindow().setAttributes(lp); 
                } 
              }); 
            } 
          }, 2000); // flashing of screen 
         } 
        });