Android 错误集锦

一、【线程相关】Can't create handler inside thread that has not called Looper.prepare()

Cause Reason：通常是在非主线程中执行了与UI相关的操作。例子如下：

/**
 * @author heg
 * @version 创建时间：2014-3-12 上午9:53:03
 * @description: 
 *               验证对话框能否从Service中弹出，不需要Activity?<br>
 * 
 */

public class DialogShowFromService extends Service {

	@Override
	public int onStartCommand(Intent intent, int flags, int startId) {
//		show();
		showDialog();
		return super.onStartCommand(intent, flags, startId);
		
	}
	
	private void showDialog() {
		new Thread(new Runnable(){
			
			@Override
			public void run() {
				try {
					Thread.sleep(5000);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
				show();
			}
			
		}).start();
		
	}
	
	private void show() {
		AlertDialog.Builder builder = new AlertDialog.Builder(getApplicationContext());
		builder.setTitle("从Service弹出来!");
		builder.create().show();
		
	}
}

二、【Context相关】Unable to add window -- token null is not for an application

Cause Reason：通常是在错误的上下文中创建View，如在Service中直接添加UI组件就不行。例子如下：

/**
 * @author heg
 * @version 创建时间：2014-3-12 上午9:53:03
 * @description: 
 *               验证对话框能否从Service中弹出，不需要Activity?<br>
 * 
 */
public class DialogShowFromService extends Service {

	@Override
	public int onStartCommand(Intent intent, int flags, int startId) {
		show();
//		showDialog();
		return super.onStartCommand(intent, flags, startId);
		
	}
	
	private void show() {
		AlertDialog.Builder builder = new AlertDialog.Builder(getApplicationContext());
		builder.setTitle("从Service弹出来!");
		builder.create().show();
		
	}
}

Ps: 上面例子的结论是：

 /*<p>结论：<br>
 * Service中可以不需要Activity弹出对话框，<br>
 * 但只能弹出系统级对话框，并且需要以下两个条件：
 * <br>dialog.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT)
 * <br>"android.permission.SYSTEM_ALERT_WINDOW"*/

三、【编译相关】如何编译第三方jar包。

#先指定库名，可以自己定义。多个有多个需要 libName1 \ libName2  这样
LOCAL_STATIC_JAVA_LIBRARIES := libName
#预编译静态库
LOCAL_PREBUILT_STATIC_JAVA_LIBRARIES := libName:libPath/libRealName
#不加上下一句会报need by /classes-full-debug.jar等错误
include $(BUILD_MULTI_PREBUILT)