import javax.swing.UIManager;
import java.awt.*;

public class HelloApp {

  public HelloApp() {
    HelloFrame frame = new HelloFrame();
    //取得屏幕大小
    Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
    //取得窗口大小
    Dimension frameSize = frame.getSize();
    //使窗口居中對齊
    frame.setLocation( (screenSize.width - frameSize.width) / 2,
                      (screenSize.height - frameSize.height) / 2);
    frame.setVisible(true);
  }

  public static void main(String[] args) {
    try {
      //以Windows風格顯示窗口
      UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
    }
    catch(Exception e) {
      e.printStackTrace();
    }
    new HelloApp();
  }
}