java - 不知道如何根据单选按钮运行图形？

Question

所以我有 1 个类，带有一个单选按钮和 1 个类，它将根据单选按钮的结果创建一个小程序。我不知道如何使图形根据 if/else 语句运行。我们将不胜感激所有帮助。

单选按钮类:

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


public class RadioButton extends JPanel {

    static JFrame frame;

   JLabel pic;
   RadioListener myListener = null;
   protected JRadioButton displacement;
   protected JRadioButton accel; 
   protected JRadioButton time;
   public RadioButton() {



       // Create the radio buttons
       displacement = new JRadioButton("Displacement");
       displacement.setMnemonic(KeyEvent.VK_N);
       displacement.setSelected(true);
        //Displacement Button, set to automatically be clicked

       accel = new JRadioButton("Acceleration");
       accel.setMnemonic(KeyEvent.VK_A);
       accel.setActionCommand("acceleration");
        //Acceleration Button

       time = new JRadioButton("Change in time");
       time.setMnemonic(KeyEvent.VK_S);
       time.setActionCommand("deltaT");
        //The change in time button


       // Creates the group of buttons
       ButtonGroup group = new ButtonGroup();
       group.add(displacement);
       group.add(accel);
       group.add(time);

              myListener = new RadioListener();
                displacement.addActionListener(myListener);
                accel.addActionListener(myListener);
                time.addActionListener(myListener);


      // Set up the picture label
       pic = new JLabel(new ImageIcon(""+"numbers" + ".jpg"));          //Set the Default Image

       pic.setPreferredSize(new Dimension(177, 122)); 


       // Puts the radio buttons down
       JPanel panel = new JPanel();
       panel.setLayout(new GridLayout(0, 1));
       panel.add(displacement);
       panel.add(accel);
       panel.add(time);


       setLayout(new BorderLayout());
       add(panel, BorderLayout.WEST);
       add(pic, BorderLayout.CENTER);
       setBorder(BorderFactory.createEmptyBorder(40,40,40,40));
   } 



   //Listening to the buttons
   class RadioListener implements ActionListener { 
       public void actionPerformed(ActionEvent e) {
           pic.setIcon(new ImageIcon(""+e.getActionCommand() 
                                         + ".jpg"));
       }
   }

   public static void main(String s[]) {
        frame = new JFrame("∆x = Vavg * time");
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {System.exit(0);}
        });

        frame.getContentPane().add(new RadioButton(), BorderLayout.CENTER);
        frame.pack();
        frame.setVisible(true);
   }
}

If/Else 语句类:

import java.lang.Object;
import java.awt.Color; 
import java.awt.Graphics;
import java.awt.*;


public class RadioButtonMain extends RadioButton {

    public static void main(String [ ] args) {
         new RadioButtonMain().doMain();
     }

     public void doMain() {
        if ( displacement.isSelected()) {

                   //option 1 for applet
                }



        if ( accel.isSelected()) {
            //Option 2 for applet
        }

        else {
            //Option 3 for applet
        }
        }
    }

如何根据是否按下变量 Accel 和 Displacement 来使图形运行？谢谢。

Answer 1

请记住，GUI 是一个事件驱动的环境，事物不会以线性方式运行。您不需要尝试自己运行方法，而是需要使用某种回调或监听器，它会告诉您程序/按钮的状态何时发生变化...

当引发 JRadioButton actionPerformed 事件时，您需要调用另一个方法来提供有关所发生情况的信息。然后，您可以在 RadioButtonMain 类中重写这些方法，并在调用它们时采取操作

这与 Observer Pattern 非常相似