Android在非UI线程中显示Toast

[java]
public void showToast(String msg){
        Looper.prepare();
        Toast.makeText(getApplicationContext(), msg, Toast.LENGTH_SHORT).show();
        Looper.loop();
    }

public void showToast(String msg){
  Looper.prepare();
  Toast.makeText(getApplicationContext(), msg, Toast.LENGTH_SHORT).show();
  Looper.loop();
}只需要加上那两句就能在非UI线程中显示Toast

[java]
Toast里面的show()
    public void show() {
      ...
        service.enqueueToast(pkg, tn, mDuration);   //把这个toast插入到一个队列里面
        ...
    }

Toast里面的show()
    public void show() {
      ...
        service.enqueueToast(pkg, tn, mDuration);   //把这个toast插入到一个队列里面
        ...
    }
[java]
Looper
public static final void prepare() {
        if (sThreadLocal.get() != null) {
            throw new RuntimeException("Only one Looper may be created per thread");
        }
       sThreadLocal.set(new Looper()); //在当前线程中创建一个Looper
    }

private Looper() {
        mQueue = new MessageQueue(); //关键在这，创建Looper都干了什么。其实是创建了消息队列
        mRun = true;
        mThread = Thread.currentThread();
    }

Looper
public static final void prepare() {
        if (sThreadLocal.get() != null) {
            throw new RuntimeException("Only one Looper may be created per thread");
        }
       sThreadLocal.set(new Looper()); //在当前线程中创建一个Looper
    }

private Looper() {
        mQueue = new MessageQueue(); //关键在这，创建Looper都干了什么。其实是创建了消息队列
        mRun = true;
        mThread = Thread.currentThread();
    }

总结下：Toast 显示的必要条件：
1：Toast 显示需要出现在一个线程的消息队列中.... 很隐蔽

补充：移动开发 , Android ,