小编mad*_* c.的帖子

我试图在JFrame窗口中用鼠标画线,当我尝试这样做时,它不起作用!请忽略菜单,我想稍后再做一些事情!我错过了什么!如果你能给我一些提示,我将不胜感激!

public class newGUI extends JFrame implements ActionListener, MouseMotionListener, MouseListener {
private static final long serialVersionUID = 1L;
public static final int WIDTH = 300;
public static final int HEIGHT = 200;
Point point1;
Point point2;
Line2D line2d;

public static void main(String[] args){
    newGUI gui = new newGUI();
    gui.setVisible(true);
}

public newGUI()
{
    super("Menu Demonstration");
    setSize(WIDTH, HEIGHT);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JMenu colorMenu = new JMenu("Choose Colors");
    JMenuItem greenChoice = new JMenuItem("GREEN");
    greenChoice.addActionListener(this);
    colorMenu.add(greenChoice);
    JMenuItem redChoice = new JMenuItem("RED");
    colorMenu.add(redChoice);
    JMenuBar …