Android解决Can't create handler inside thread that has not called Looper.prepare()

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在Android子线程中使用Toast时会报错：

• 代码：

Toast.makeText(this, "", Toast.LENGTH_LONG) .show()；

• 报错：

java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()

• 解决方案：

  方案一：增加Looper.prepare();

  Looper.prepare();
  Toast.makeText(this, "", Toast.LENGTH_LONG) .show()；
  Looper.loop();// 进入loop中的循环，查看消息队列

  方案二：post 给主线程去处理

  mainHandler.post(new Runnable() {
  
   @Override
   public void run() {
      if (toast == null) {
         toast = Toast.makeText(context, "",     Toast.LENGTH_SHORT);
  }
  toast.setText(msg);
  toast.setDuration(Toast.LENGTH_SHORT);
  toast.show();
   }
  });