问题描述

onKeyDown() 不能在继承类上运行

我创建了一个自定义 GalleryView，在 Samsung Galaxy S III 或者 Nexus 4 上都可以执行。当我在模拟器中运行的时候，出现下面的错误:

02-24 01:01:03.593: E/AndroidRuntime(3429): FATAL EXCEPTION: Thread-11
02-24 01:01:03.593: E/AndroidRuntime(3429): android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
02-24 01:01:03.593: E/AndroidRuntime(3429):     at android.view.ViewRoot.checkThread(ViewRoot.java:2802)
02-24 01:01:03.593: E/AndroidRuntime(3429):     at android.view.ViewRoot.playSoundEffect(ViewRoot.java:2581)
02-24 01:01:03.593: E/AndroidRuntime(3429):     at android.view.View.playSoundEffect(View.java:8516)
02-24 01:01:03.593: E/AndroidRuntime(3429):     at android.widget.Gallery.onKeyDown(Gallery.java:1109)
02-24 01:01:03.593: E/AndroidRuntime(3429):     at com.example.coverflow.ui.galleryView$1.run(galleryView.java:55)
02-24 01:01:03.593: E/AndroidRuntime(3429):     at java.lang.Thread.run(Thread.java:1096)

这些错误涉及到下面的代码:

public void startSlideShow(final int periodTime)
{
    final Runnable __runnable = new Runnable()
    {
        @Override
        public void run()
        {
            if (!isTouched)
                galleryView.this.onKeyDown(KeyEvent.KEYCODE_DPAD_RIGHT, null);
            mHandler.postDelayed(this, periodTime);
        }
    };
    new Thread(__runnable).start();

    this.setOnTouchListener(new View.OnTouchListener()
    {
        @Override
        public boolean onTouch(View view, MotionEvent event)
        {
            int currentEvent = event.getAction();
            if (currentEvent == MotionEvent.ACTION_DOWN
                    || currentEvent == MotionEvent.ACTION_MOVE)
                isTouched = true;
            else
            {
                isTouched = false;
                // Reset handler
                mHandler.removeCallbacks(__runnable);
                mHandler.postDelayed(__runnable, periodTime);
            }
            return false;
        }
    });
}

如何处理这个问题？

Line 55 是galleryView.this.onKeyDown(KeyEvent.KEYCODE_DPAD_RIGHT, null);

解决方案

 galleryView.this.onKeyDown(KeyEvent.KEYCODE_DPAD_RIGHT, null);

你这一句是在你自己new的thread里面执行的。所以会报错。
用

mHandler.post(__runnable);
new Thread(__runnable).start();

这个不需要

解决方案二：

你可以从其他线程中更新 UI，而不是activity UI 线程。
就比如错误提示：

Only the original thread that created a view hierarchy can touch its views.

使用 runOnUIThread(new Runnable{ ... }()) 将文件访问代码打包

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;
public class MainActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    MainActivity.this.runOnUiThread(new Runnable() {
         public void run() {
            Toast.makeText(MainActivity.this, "This is Toast!!!", Toast.LENGTH_SHORT).show();
    }
    });
}
}