如何在JRadioButtons中使用ActionListener

Question

我想在Java中做一個非常簡單的「Paint」。 現在我有麻煩了，因爲我不知道如何使用JRaddioButtons中的actionListener來更改我想繪製的線的顏色。

我告訴我的代碼，如果後悔過大：

import java.awt.Color; 
import java.awt.Graphics; 
import java.awt.Graphics2D; 
import java.awt.Point; 
import java.awt.Shape; 
import java.awt.event.MouseAdapter; 
import java.awt.event.MouseEvent; 
import java.awt.event.MouseMotionAdapter; 
import java.awt.geom.Line2D; 
import java.util.ArrayList; 
import javax.swing.JComponent; 
import javax.swing.JFrame; 
import java.awt.*; 
import java.awt.event.*; 
import javax.swing.JMenu; 
import javax.swing.JMenuItem; 
import javax.swing.JRadioButtonMenuItem; 
import javax.swing.ButtonGroup; 
import javax.swing.JMenuBar; 
import javax.swing.KeyStroke; 
import java.awt.event.*; 
import javax.swing.*; 
import javax.swing.event.*; 
import javax.swing.JPanel; 
import javax.swing.JFrame; 



public class Dibujar extends JComponent { 

    private Point inicioArrastre; 
    private Point finArrastre; 
    private ArrayList<Shape> lineas = new ArrayList<Shape>(); 


    public Dibujar() { 
     super(); 
     addMouseListener(new MouseAdapter() { 

      public void mousePressed(MouseEvent e) { // cuando se presiona el mouse 
       inicioArrastre = new Point(e.getX(), e.getY()); 
       repaint(); 
      } 

      public void mouseReleased(MouseEvent e) { // cuando se deja de presionar el mouse 
       finArrastre = new Point(e.getX(), e.getY()); 
       Shape linea = crearLinea(inicioArrastre.x, inicioArrastre.y, finArrastre.x, finArrastre.y); 
       lineas.add(linea); 
       repaint(); 
      } 
     }); 
     addMouseMotionListener(new MouseMotionAdapter() { 

      public void mouseDragged(MouseEvent e) { // cuando se esta arrastrando el mouse 
       finArrastre = new Point(e.getX(), e.getY()); 
       Shape linea = crearLinea(inicioArrastre.x, inicioArrastre.y, finArrastre.x, finArrastre.y); 
       lineas.add(linea); 
       inicioArrastre = new Point(finArrastre.x, finArrastre.y); 
       repaint(); 
      } 
     }); 
    } 

    public void paint(Graphics g) { 
     Graphics2D g2 = (Graphics2D) g; 
     g2.setColor(Color.RED); 
     for (Shape linea : lineas) { // dibuja todos las elipses 
      g2.draw(linea); 
     } 
    } 

    private Line2D.Float crearLinea(int x1, int y1, int x2, int y2) { 
     return new Line2D.Float(x1, y1, x2, y2); 
    } 

    public static void main(String[] a3d) { 
     Dibujar dibu = new Dibujar(); 
     JFrame ventana = new JFrame("Dibujar"); 
     ventana.setJMenuBar(dibu.createMenuBar()); 
     ventana.setSize(400, 300); 
     ventana.setLocationRelativeTo(null); 
     ventana.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     ventana.add(new Dibujar()); 
     ventana.setVisible(true); 
    } 


    public JMenuBar createMenuBar() { 
     JMenuBar menuBar; 
     JMenu menu, submenu; 
     JMenuItem menuItem; 
     JRadioButtonMenuItem rbMenuItem; 

     //Create the menu bar. 
     menuBar = new JMenuBar(); 

     //Build the first menu. 
     menu = new JMenu("A Menu"); 
     menu.setMnemonic(KeyEvent.VK_A); 
     menu.getAccessibleContext().setAccessibleDescription(
       "The only menu in this program that has menu items"); 
     menuBar.add(menu); 

     //a group of JMenuItems 
     menuItem = new JMenuItem("Select a Color", 
           KeyEvent.VK_T); 
     //menuItem.setMnemonic(KeyEvent.VK_T); //used constructor instead 
     menuItem.setAccelerator(KeyStroke.getKeyStroke(
       KeyEvent.VK_1, ActionEvent.ALT_MASK)); 
     menuItem.getAccessibleContext().setAccessibleDescription(
       "This doesn't really do anything"); 
     menu.add(menuItem); 


     menuItem.setMnemonic(KeyEvent.VK_B); 
     menu.add(menuItem); 


     menuItem.setMnemonic(KeyEvent.VK_D); 
     menu.add(menuItem); 

     //a group of radio button menu items 
     menu.addSeparator(); 
     ButtonGroup group = new ButtonGroup(); 

     rbMenuItem = new JRadioButtonMenuItem("RED"); 
     rbMenuItem.setSelected(true); 
     rbMenuItem.setMnemonic(KeyEvent.VK_R); 
     rbMenuItem.addActionListener(null); 
     group.add(rbMenuItem); 
     menu.add(rbMenuItem); 

     rbMenuItem = new JRadioButtonMenuItem("BLUE"); 
     rbMenuItem.setMnemonic(KeyEvent.VK_B); 
     group.add(rbMenuItem); 
     menu.add(rbMenuItem); 



     return menuBar; 
    } 
    } 

感謝你這麼多！

Answer 1

你只需要一個actionPerformed方法

RadioButton.addActionListener(new ActionListener() 
{ 
    public void actionPerformed(ActionEvent e) 
    { 
    // Enter your code, to change the color  
    } 
});