[Android]android.util.AndroidRuntimeException: requestFeature() must be called before adding content

E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.kandy.kingplayer/com.kandy.kingplayer.LoginActivity}: android.util.AndroidRuntimeException: requestFeature() must be called before adding content
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2198)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2248)
at android.app.ActivityThread.access$600(ActivityThread.java:145)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1246)

其实遇到这样的错误是有按照要求在调用requestFeature的时候，放到setContentView之前的：

 protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.requestWindowFeature(Window.FEATURE_NO_TITLE);

        setContentView(R.layout.activity_login);
    }

但是仍然出现了这样的异常，实际上调用requestWindowFeature的目的是不想显示标题栏。

为什么这个地方会出现异常呢？是因为这里继承的不是Activity，而是继承了AppCompatActivity，其中AppCompatActivity又继承了Toolbar，所以上述代码编译是没有问题的，一旦运行就会出现异常的，那么正确的做法是什么呢？修改代码如下：

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
// this.requestWindowFeature(Window.FEATURE_NO_TITLE);
        ActionBar actionBar = getSupportActionBar();
        actionBar.hide();

        setContentView(R.layout.activity_login);
    }