AndroidRuntimeException: requestFeature() must be called before adding content

requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.activity_main);

     
     
     
     

      
      
      
      增加代码requestWindowFeature(Window.FEATURE_NO_TITLE)以去掉标题栏，并且代码放在
      
      
      
      setContentView之前，但还是报异常
      
      
      
      

      
      
      
      android.util.
      
      
      
      AndroidRuntimeException: requestFeature() must be called before adding content
将
      
      
      
      AppCompatActivity改为Activity才得以解决。不知道AppCompatActivity和Activity有何区别。
      
      
      
      

      
      
      
      
参考：
      
      
      
      http://www.cnblogs.com/and_he/archive/2011/06/01/2067106.html 
      
      
      
      Android中全屏或者取消标题栏