Handler.postDelayed()无效

在项目使用 Handler.postDelayed() 延时执行任务，却发现无效，代码如下：

private Handler mHandler = new Handler();
boolean ret = mHandler.postDelayed(new Runnable() {
@Override
public void run() {

                                    }
                                }, delay);

Log.d(“Nat”, “postDelayed:” + ret);
修改后的代码如下：

private Handler mHandler = new Handler(Looper.getMainLooper());
boolean ret = mHandler.postDelayed(new Runnable() {
@Override
public void run() {

                                    }
                                }, delay);

Log.d(“Nat”, “postDelayed:” + ret);
总结：需要给Handler设置一个主线程的 looper。