Android中Handler使用postDelayed方法不生效

需在主線程中操作

方法1（推薦）:

new Handler(Looper.getMainLooper()).postDelayed(new Runnable() {
    @Override
    public void run() {
        doSomething();
    }
},2000);

方法2:

runOnUiThread(new Runnable() {
    @Override
    public void run() {
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                doSomething();
            }
        },2000);
    }
}