java swing设置frame的高度或图标

  Toolkit kit = Toolkit.getDefaultToolkit();
       
        Dimension dimension = kit.getScreenSize();
       
        int screenHeight = dimension.height;
        int screenWidth = dimension.width;
       
        setSize(screenWidth / 2, screenHeight / 2);
       
        setLocationByPlatform(true);
       
        Image img = kit.getImage(this.getClass().getResource("Nbrcats2_icon[1].gif"));
       
        setIconImage(img);
       
        setTitle("SizedFrame");