Activity全屏的方法

 @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);

       /*set it to be full screen*/
       requestWindowFeature(Window.FEATURE_NO_TITLE);
       getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

        setContentView(R.layout.activity_main);
    }

需要注意的是：

requestWindowFeature(Window.FEATURE_NO_TITLE);
       getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

这两行代码必须放在setContentView()方法之前。