与actionListener静态类冲突

Question

我正在寻找一些方向。我想要一个按钮来为绘制在图形内容上的东西提供动力。我以前用jframes和listeners使用过按钮。但不知怎的，听众并未被接受。我相信这与宣布的两个类别有关。有谁能告诉我问题是什么或冲突？

我不能使用//f.addWindowListener(this）; //b.addActionListener（this）; 它标志着错误，这就是为什么他们被写成评论... = S

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

/* implements ActionListener*/ 
class JFramePaint1 extends JFrame implements ActionListener { 

    public static int activa = 0; 
    public static JButton b = new JButton("b"); 

    public static void main(String[] a) { 

     JFrame f = new JFrame(); 
     f.setTitle("Drawing Graphics in Frames"); 
     f.setSize(800, 650); 
     f.setLocation(200, 50); 
     f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 

     f.setContentPane(new ContentComponent()); 
     f.getContentPane().add(b); 

     //f.addWindowListener(this); 
     //b.addActionListener(this); 

     f.setVisible(true); 
    } 

    static class ContentComponent extends JPanel { 

     public void paint(Graphics g) { 
      g.setColor(Color.RED); 
      g.fillRect(0, 40, 800, 650); 
      if (activa == 1) { 

       g.setColor(Color.BLACK); 
       g.drawRect(40, 40, 150, 80); 
       int x = 40; 
       int y = 40; 
       for (int i = 0; i < 4; i++) { 

        g.drawRect(x + 10, y + 10, 150, 80); 
        x = x + 10; 
        y = y + 10; 
       } 
      } 
     }//del paint 
    } 

    public void actionPerformed(ActionEvent e) { 
     if (e.getSource() == b) { 
      System.out.println("entro"); 
     } 
    } 

    public void windowClosing(WindowEvent e) { 
     System.exit(0); 
    } 

    public void windowOpened(WindowEvent e) {} 

    public void windowClosed(WindowEvent e) {} 

    public void windowActivated(WindowEvent e) {} 

    public void windowDeactivated(WindowEvent e) {} 

    public void windowIconified(WindowEvent e) {} 

    public void windowDeiconified(WindowEvent e) {} 
} 

Answer 1

，因为你在一个静态方法是不能使用

//f.addWindowListener(this); 
    //b.addActionListener(this); 

。你认为this指向什么？

Answer 2

您可能会发现将main（）中的所有代码移动到构造函数中更容易。 Fwiw，我也不知道你为什么要扩展JFrame，但也在你的主要方法中创建一个新的JFrame实例。我想你想要这样的东西（我还没有测试过，但这是一般的想法）。

FWIW，你可能想要阅读一个好的Java语言教程，以正确理解“静态”的含义。

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

/* implements ActionListener*/ 
class JFramePaint1 extends JFrame implements ActionListener { 

    private int activa = 0; 
    private JButton b = new JButton("b"); 

    JFramePaint1() { 
     setTitle("Drawing Graphics in Frames"); 
     setSize(800, 650); 
     setLocation(200, 50); 
     setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 

     setContentPane(new ContentComponent()); 
     getContentPane().add(b); 

     addWindowListener(this); 
     addActionListener(this); 
    } 

    public static void main(String[] a) { 
     new JFramePaint1().setVisible(true); 
    } 

    class ContentComponent extends JPanel { 

     public void paint(Graphics g) { 
      g.setColor(Color.RED); 
      g.fillRect(0, 40, 800, 650); 
      if (activa == 1) { 

       g.setColor(Color.BLACK); 
       g.drawRect(40, 40, 150, 80); 
       int x = 40; 
       int y = 40; 
       for (int i = 0; i < 4; i++) { 

        g.drawRect(x + 10, y + 10, 150, 80); 
        x = x + 10; 
        y = y + 10; 
       } 
      } 
     }//del paint 
    } 

    public void actionPerformed(ActionEvent e) { 
     if (e.getSource() == b) { 
      System.out.println("entro"); 
     } 
    } 

    public void windowClosing(WindowEvent e) { 
     System.exit(0); 
    } 

    public void windowOpened(WindowEvent e) {} 

    public void windowClosed(WindowEvent e) {} 

    public void windowActivated(WindowEvent e) {} 

    public void windowDeactivated(WindowEvent e) {} 

    public void windowIconified(WindowEvent e) {} 

    public void windowDeiconified(WindowEvent e) {} 
}