java更改一个类变量的值，然后在另一个类中调用它

Question

我目前正在做一个项目，其中生成了2个0到20之间的随机整数。还选择了一个随机运算符（+、-、或*）

用户必须在3次尝试中输入正确答案。如果他们第一次尝试成功，他们将获得5分，第二次尝试获得3分，第三次尝试获得1分。如果三次尝试后仍然没有得到正确答案，他们将得到0分，并生成一组新的数字和一个运算符

我的问题是：当我运行测试仪并输入我的答案时，成功尝试的次数增加了1，但点数保持在0。我做了一些故障排除，发现pt<--（用户拥有的点数）保持为0（其初始化值），因为答案的值保持为0，即使随机化（）方法中的switch语句更改了答案的值

以下是我的项目代码：

1st Class（Adder.java）：

package adder;

import java.util.Random;

    public class Adder 
    {
        int int1 = 0;
        int int2 = 0;
        int answer = 0;
        String operator;

        public int randomize()
        {
            Random rnd1 = new Random();

            int1 = rnd1.nextInt(21);
            int2 = rnd1.nextInt(21);
            int op = rnd1.nextInt(3);

            switch(op)
            {
                case 0:
                    operator = "+";
                    answer = int1 + int2;
                    break;

                case 1:
                    operator = "-";
                    answer = int1 - int2;
                    break;

                case 2:
                    operator = "*";
                    answer = int1 * int2;
                    break;
            }

            //Test
            System.out.println(int1);
            System.out.println(int2);
            System.out.println(operator);
            System.out.println(answer);

            return answer;
       }

     public static void main(String[] args) 
     {
         //Test
         //Adder a = new Adder();   
         //a.randomize();
     }
}

第二课堂（AdderGame.java）：

package adder;

public class AdderGame 
{
    //1 try = 5 pt, 2 try = 3 pt, 3 try = 1 pt

    int numTries = 0;
    //Number of points the user has, init to 0
    int pt = 0;
    Adder checker = new Adder();

    public int checkAnswer(int a)
    {
        System.out.println("CHECKER.ANSWER = " + checker.answer);

        if (a == checker.answer)
        {
            numTries++;

            switch(numTries)
            {
                case 1:
                    pt = pt + 5;
                    break;

                case 2:
                    pt = pt + 3;
                    break;

                case 3:
                    pt++;
                    break;
            }
        }

        else if (a != checker.answer)
        {
            //Another test output, to see if this loop is entered or not
            System.out.println("INCORRECT");
        }

        return pt;
    }
}

3rd Class（AdderTester.java）（GUI）：

package adder;

public class AdderTester extends javax.swing.JFrame
{
    //Create objects from the other two classes
    Adder adder = new Adder();
    AdderGame checker = new AdderGame();

    public AdderTester() {
        initComponents();
        adder.randomize();
        num1Label.setText(Integer.toString(adder.int1));
        num2Label.setText(Integer.toString(adder.int2));
        opLabel.setText(adder.operator);
    }

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {
        jPanel1 = new javax.swing.JPanel();
        jLabel1 = new javax.swing.JLabel();
        num1Label = new javax.swing.JLabel();
        opLabel = new javax.swing.JLabel();
        num2Label = new javax.swing.JLabel();
        answerTextfield = new javax.swing.JTextField();
        confirmButton = new javax.swing.JButton();
        jLabel2 = new javax.swing.JLabel();
        ptLabel = new javax.swing.JLabel();
        jLabel3 = new javax.swing.JLabel();
        numTriesLabel = new javax.swing.JLabel();
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        getContentPane().setLayout(new org.netbeans.lib.awtextra.AbsoluteLayout());

        jPanel1.setBackground(new java.awt.Color(54, 69, 79));
        jPanel1.setLayout(new org.netbeans.lib.awtextra.AbsoluteLayout());

        jLabel1.setFont(new java.awt.Font("Dialog", 1, 36)); // NOI18N
        jLabel1.setForeground(new java.awt.Color(255, 255, 255));
        jLabel1.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        jLabel1.setText("Adder");
        jPanel1.add(jLabel1, new org.netbeans.lib.awtextra.AbsoluteConstraints(0, 10, 450, -1));

        num1Label.setFont(new java.awt.Font("Dialog", 0, 16)); // NOI18N
        num1Label.setForeground(new java.awt.Color(255, 255, 255));
        num1Label.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        num1Label.setText("num1");
        jPanel1.add(num1Label, new org.netbeans.lib.awtextra.AbsoluteConstraints(90, 100, -1, -1));

        opLabel.setFont(new java.awt.Font("Dialog", 0, 16)); // NOI18N
        opLabel.setForeground(new java.awt.Color(255, 255, 255));
        opLabel.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        opLabel.setText("op");
        jPanel1.add(opLabel, new org.netbeans.lib.awtextra.AbsoluteConstraints(200, 100, 40, -1));

        num2Label.setFont(new java.awt.Font("Dialog", 0, 16)); // NOI18N
        num2Label.setForeground(new java.awt.Color(255, 255, 255));
        num2Label.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        num2Label.setText("num2");
        jPanel1.add(num2Label, new org.netbeans.lib.awtextra.AbsoluteConstraints(290, 100, -1, -1));

        answerTextfield.setFont(new java.awt.Font("Dialog", 0, 14)); // NOI18N
        jPanel1.add(answerTextfield, new org.netbeans.lib.awtextra.AbsoluteConstraints(90, 140, 260, -1));

        confirmButton.setFont(new java.awt.Font("Dialog", 0, 16)); // NOI18N
        confirmButton.setText("Confirm");
        confirmButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                confirmButtonActionPerformed(evt);
            }
        });
        jPanel1.add(confirmButton, new org.netbeans.lib.awtextra.AbsoluteConstraints(180, 310, -1, -1));

        jLabel2.setBackground(new java.awt.Color(255, 255, 255));
        jLabel2.setFont(new java.awt.Font("Dialog", 0, 16)); // NOI18N
        jLabel2.setForeground(new java.awt.Color(255, 255, 255));
        jLabel2.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        jLabel2.setText("Current Points:");
        jPanel1.add(jLabel2, new org.netbeans.lib.awtextra.AbsoluteConstraints(170, 180, -1, -1));

        ptLabel.setBackground(new java.awt.Color(255, 255, 255));
        ptLabel.setFont(new java.awt.Font("Dialog", 0, 14)); // NOI18N
        ptLabel.setForeground(new java.awt.Color(255, 255, 255));
        ptLabel.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        ptLabel.setText("pt");
        jPanel1.add(ptLabel, new org.netbeans.lib.awtextra.AbsoluteConstraints(190, 210, 60, -1));

        jLabel3.setBackground(new java.awt.Color(255, 255, 255));
        jLabel3.setFont(new java.awt.Font("Dialog", 0, 16)); // NOI18N
        jLabel3.setForeground(new java.awt.Color(255, 255, 255));
        jLabel3.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        jLabel3.setText("Number of Tries:");
        jPanel1.add(jLabel3, new org.netbeans.lib.awtextra.AbsoluteConstraints(140, 240, 170, -1));

        numTriesLabel.setBackground(new java.awt.Color(255, 255, 255));
        numTriesLabel.setFont(new java.awt.Font("Dialog", 0, 16)); // NOI18N
        numTriesLabel.setForeground(new java.awt.Color(255, 255, 255));
        numTriesLabel.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        numTriesLabel.setText("numTries");
        jPanel1.add(numTriesLabel, new org.netbeans.lib.awtextra.AbsoluteConstraints(170, 270, 110, -1));

        getContentPane().add(jPanel1, new org.netbeans.lib.awtextra.AbsoluteConstraints(0, 0, 450, 350));

        pack();
    }// </editor-fold>                        

    private void confirmButtonActionPerformed(java.awt.event.ActionEvent evt) {                                              
        //Holds the value for the answer the user inputs
        int userAns = Integer.valueOf(answerTextfield.getText());
        //Holds the value for the answer

        System.out.println("answer = ");
        checker.checkAnswer(userAns);

        ptLabel.setText(String.valueOf(checker.pt));
        numTriesLabel.setText(String.valueOf(checker.numTries));
    }                                             

    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(AdderTester.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(AdderTester.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(AdderTester.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(AdderTester.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new AdderTester().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JTextField answerTextfield;
    private javax.swing.JButton confirmButton;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JLabel num1Label;
    private javax.swing.JLabel num2Label;
    private javax.swing.JLabel numTriesLabel;
    private javax.swing.JLabel opLabel;
    private javax.swing.JLabel ptLabel;
    // End of variables declaration                   
}

Answer 1

您正在创建Adder的两个实例，一个在AdderGame中，另一个在AdderTester中。因为它们是不同的对象，你的比较在checkAnswer()中失败了。与其在AdderGame中创建Adder的新对象，不如将其作为AdderGame构造函数的参数