在java中控制循环执行速度 - Android

时间:2013-02-05 13:17:35

标签: java android loops imageview thread-sleep

我知道这是一个非常小的问题。但我无法弄清楚原因。在我的程序中,我运行循环50次。在循环内部,我生成一个0到5的随机整数,并将图像(骰子图像)加载到imageView。所以imageView应该快速变化,我应该能够看到一些视觉上像骰子值正在快速变化。

但是我在imageView中看不到任何这样的变化,在循环结束时,imageView立即改变。我的意思是如果初始骰子值为2,它将保持为2,直到循环结束,然后imageView突然变为5或某些这样的价值。

我意识到我无法看到骰子imageView的变化,因为循环执行速度非常快。然后经过Loop execution speed control后我放了Thread.sleep方法,但仍然没有变化。

这是我的代码:

ImageView dice = (ImageView) findViewById(R.id.imageViewrollingdiceOne);
for (int i=0;i<50;i++){
        int randomNum = random.nextInt(6);
        System.out.println("Random Value"+randomNum);
        dice.setImageResource(images[randomNum]);
        try {
            Thread.sleep(200);
        } catch (Exception e) {
            System.out.println("ex called");
        }
    }

有人可以解释一下这个原因吗?我在logcat中没有收到任何错误。

这是logcat:

02-05 18:38:38.515: D/OpenGLRenderer(27058): Flushing caches (mode 0)
02-05 18:38:42.179: D/TextLayoutCache(27455): Using debug level: 0 - Debug Enabled: 0
02-05 18:38:42.239: D/libEGL(27455): loaded /system/lib/egl/libGLES_android.so
02-05 18:38:42.239: D/libEGL(27455): loaded /system/lib/egl/libEGL_mali.so
02-05 18:38:42.249: D/libEGL(27455): loaded /system/lib/egl/libGLESv1_CM_mali.so
02-05 18:38:42.249: D/libEGL(27455): loaded /system/lib/egl/libGLESv2_mali.so
02-05 18:38:42.279: D/OpenGLRenderer(27455): Enabling debug mode 0
02-05 18:38:50.146: D/OpenGLRenderer(27455): Flushing caches (mode 0)
02-05 18:38:52.148: I/System.out(27455): Random Value0
02-05 18:38:52.348: I/System.out(27455): Random Value4
02-05 18:38:52.579: I/System.out(27455): Random Value2
02-05 18:38:52.789: I/System.out(27455): Random Value1
02-05 18:38:53.029: I/System.out(27455): Random Value2
02-05 18:38:53.219: I/System.out(27455): Random Value4
02-05 18:38:53.420: I/System.out(27455): Random Value1
02-05 18:38:53.620: I/System.out(27455): Random Value1
02-05 18:38:53.830: I/System.out(27455): Random Value5
02-05 18:38:53.870: D/dalvikvm(27455): GC_CONCURRENT freed 1035K, 11% free 9856K/10979K, paused 12ms+2ms
02-05 18:38:54.070: I/System.out(27455): Random Value1
02-05 18:38:54.300: I/System.out(27455): Random Value5
02-05 18:38:54.501: I/System.out(27455): Random Value1
02-05 18:38:54.701: I/System.out(27455): Random Value4
02-05 18:38:54.931: I/System.out(27455): Random Value1
02-05 18:38:55.131: I/System.out(27455): Random Value1 
02-05 18:38:55.331: I/System.out(27455): Random Value1
02-05 18:38:55.532: I/System.out(27455): Random Value1
02-05 18:38:55.732: I/System.out(27455): Random Value1
02-05 18:38:55.942: I/System.out(27455): Random Value3
02-05 18:38:56.162: I/System.out(27455): Random Value1
02-05 18:38:56.362: I/System.out(27455): Random Value4
02-05 18:38:56.563: I/System.out(27455): Random Value5
02-05 18:38:56.763: I/System.out(27455): Random Value0
02-05 18:38:56.973: I/System.out(27455): Random Value2
02-05 18:38:57.193: I/System.out(27455): Random Value4
02-05 18:38:57.393: I/System.out(27455): Random Value3
02-05 18:38:57.594: I/System.out(27455): Random Value4
02-05 18:38:57.794: I/System.out(27455): Random Value4
02-05 18:38:58.004: I/System.out(27455): Random Value0
02-05 18:38:58.204: I/System.out(27455): Random Value0 
02-05 18:38:58.404: I/System.out(27455): Random Value5
02-05 18:38:58.605: I/System.out(27455): Random Value0
02-05 18:38:58.805: I/System.out(27455): Random Value5
02-05 18:38:59.005: I/System.out(27455): Random Value0
02-05 18:38:59.215: I/System.out(27455): Random Value2
02-05 18:38:59.415: I/System.out(27455): Random Value5
02-05 18:38:59.616: I/System.out(27455): Random Value2
02-05 18:38:59.816: I/System.out(27455): Random Value5
02-05 18:39:00.016: I/System.out(27455): Random Value4
02-05 18:39:00.216: I/System.out(27455): Random Value3
02-05 18:39:00.416: I/System.out(27455): Random Value4
02-05 18:39:00.617: I/System.out(27455): Random Value4
02-05 18:39:00.817: I/System.out(27455): Random Value1
02-05 18:39:01.027: I/System.out(27455): Random Value5
02-05 18:39:01.227: I/System.out(27455): Random Value3
02-05 18:39:01.427: I/System.out(27455): Random Value3
02-05 18:39:01.628: I/System.out(27455): Random Value5
02-05 18:39:01.828: I/System.out(27455): Random Value2 
02-05 18:39:02.028: I/System.out(27455): Random Value0
02-05 18:39:02.228: I/System.out(27455): Random Value2

2 个答案:

答案 0 :(得分:3)

使用Thread.sleep创建一个Thread或使用Handler for make wait来更改ImageView中的图像,而不是睡眠主UI线程:

new Handler().postDelayed(new Runnable() {
       public void run() {

            // put your code here to change image in ImageView...

       }
     }, 200);

答案 1 :(得分:1)

我解决了这个问题。以上答案也非常有用。

在run方法中使用以下内容。

handler.postDelayed(this, 200);

它有效。这是完整的答案。参考this

final Handler handler = new Handler();
Handler.postDelayed(new Runnable(){
public void run(){
    int randomNum = random.nextInt(6);
    dice.setImageResource(images[randomNum]);
    handler.postDelayed(this, 200);
    }
 }, 200);

感谢。