Java 如何从一个类到另一个Action Listener类获取变量信息？

这是我的两个文件类的代码。为了在action listener JFrame中传输和打印变量，我必须添加/修复什么？在类型“Next”中发现错误“No field named”（我在主类的action listener中使用的变量）

ActionListener：

import java.awt.*; //for Dimension
import javax.swing.*; //for GUI components
import java.awt.event.*; //for MessageListener

public class Next implements ActionListener
{
 public void actionPerformed (ActionEvent event)
 {
    //Output frame
    JFrame frame2 = new JFrame ();
    frame2.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
    frame2.setSize (new Dimension (300, 250));
    frame2.setTitle ("Mortgage Calculator");
    frame2.getContentPane ().setLayout (new BorderLayout ());

    JPanel westPanel2 = new JPanel (new GridLayout (3, 1));
    JLabel nameLabel = new JLabel ("Name: " + name);
    westPanel2.add (nameLabel);
    JLabel ageLabel = new JLabel ("Age: " + age);
    westPanel2.add (ageLabel);
    JLabel incomeLabel = new JLabel ("Yearly Income: " + income);
    westPanel2.add (incomeLabel);
    frame2.getContentPane ().add (westPanel2, BorderLayout.WEST);

    JPanel centerPanel2 = new JPanel (new GridLayout (3, 1));
    JLabel priceLabel = new JLabel ("    Price of property: " + price);
    centerPanel2.add (priceLabel);
    JLabel downPayLabel = new JLabel ("    Down Payment: " + downPay);
    centerPanel2.add (downPayLabel);
    JLabel interestRateLabel = new JLabel ("    Interest Rate: " + income);
    centerPanel2.add (interestRateLabel);
    frame2.getContentPane ().add (centerPanel2, BorderLayout.CENTER);

    frame2.pack ();
    frame2.setVisible (true);

  }
}

---

main方法中的变量是局部变量，因此侦听器将无法看到它们

有很多方法可以解决此问题。首先，您必须使状态变量（

name

等）成为

MortgageCalculator

类的成员变量，以便其他方法或类可以看到它们。然后，让侦听器代码访问这些变量。一些选项：

• 使

  Next

  成为

  MortgageCalculator

  的内部类，以便它可以自动查看成员变量
• 使

  MortgageCalculator

  实现

  ActionListener

  ，并将

  actionPerformed

  方法移动到结果类中。然后，您可以说

  nextButton.addActionListener（new Next（））；

  ，而不是编写

  nextButton.addActionListener（this）；

  ，但只能在非静态方法中（因此不是

  main

  ——您需要对

  MortgageCalculator

  的实例进行

  main

  调用非静态方法）

import java.awt.*; //for Dimension
import javax.swing.*; //for GUI components
import java.awt.event.*; //for MessageListener

public class Next implements ActionListener
{
 public void actionPerformed (ActionEvent event)
 {
    //Output frame
    JFrame frame2 = new JFrame ();
    frame2.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
    frame2.setSize (new Dimension (300, 250));
    frame2.setTitle ("Mortgage Calculator");
    frame2.getContentPane ().setLayout (new BorderLayout ());

    JPanel westPanel2 = new JPanel (new GridLayout (3, 1));
    JLabel nameLabel = new JLabel ("Name: " + name);
    westPanel2.add (nameLabel);
    JLabel ageLabel = new JLabel ("Age: " + age);
    westPanel2.add (ageLabel);
    JLabel incomeLabel = new JLabel ("Yearly Income: " + income);
    westPanel2.add (incomeLabel);
    frame2.getContentPane ().add (westPanel2, BorderLayout.WEST);

    JPanel centerPanel2 = new JPanel (new GridLayout (3, 1));
    JLabel priceLabel = new JLabel ("    Price of property: " + price);
    centerPanel2.add (priceLabel);
    JLabel downPayLabel = new JLabel ("    Down Payment: " + downPay);
    centerPanel2.add (downPayLabel);
    JLabel interestRateLabel = new JLabel ("    Interest Rate: " + income);
    centerPanel2.add (interestRateLabel);
    frame2.getContentPane ().add (centerPanel2, BorderLayout.CENTER);

    frame2.pack ();
    frame2.setVisible (true);

  }
}