java - 需要打印我的二维数组，但它只在输出框中显示一个点

Question

我正在学习 12 年级编程的在线类(class)，我们在 net beans 中使用 java 应用程序。我们需要创建一个程序，显示输入的学生 4 个测试成绩，最多 15 个学生。

我已经将其设置为这样的数组

private void addButtonActionPerformed(java.awt.event.ActionEvent evt) {                                          
    String testOne = test1Input.getText();
    String testTwo = test2Input.getText();
    String testThree = test3Input.getText();
    String testFour = test4Input.getText();
    String studentNames = (firstInput.getText() + " " + secondInput.getText());

    students[next][0] = studentNames;
    students[next][1] = testOne;
    students[next][2] = testTwo;
    students[next][3] = testThree;
    students[next][4] = testFour;
    next++;
}

当我使用它来显示它时

private void listButoonActionPerformed(java.awt.event.ActionEvent evt) {                                           
    for (int row = 0; row <= 15; row++) {
        for (int col = 0; col <= 4; col++) {
            outBox.setText(students[row][col] + " ");
        }
    }
} 

它只显示第三个测试标记

/* * 要更改此许可证 header ，请在项目属性中选择许可证 header 。 * 要更改此模板文件，请选择“工具”|“模板 * 并在编辑器中打开模板。 */打包学生成绩；

/** * * @作者斯图巴 */公共(public)类 UI 扩展 javax.swing.JFrame {

public static String[][] students = new String[15][4];
public static int next = 0;

/**
 * Creates new form UI
 */
public UI() {
    initComponents();

}

/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    jPanel1 = new javax.swing.JPanel();
    title = new javax.swing.JLabel();
    firstLabel = new javax.swing.JLabel();
    secondLabel = new javax.swing.JLabel();
    firstInput = new javax.swing.JTextField();
    secondInput = new javax.swing.JTextField();
    test1 = new javax.swing.JLabel();
    test2 = new javax.swing.JLabel();
    test3 = new javax.swing.JLabel();
    test4 = new javax.swing.JLabel();
    test1Input = new javax.swing.JTextField();
    test2Input = new javax.swing.JTextField();
    test3Input = new javax.swing.JTextField();
    test4Input = new javax.swing.JTextField();
    addButton = new javax.swing.JButton();
    listButton = new javax.swing.JButton();
    stundentAvButton = new javax.swing.JButton();
    courseAvButton = new javax.swing.JButton();
    exit = new javax.swing.JButton();
    jScrollPane1 = new javax.swing.JScrollPane();
    outBox = new javax.swing.JTextPane();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    jPanel1.setBackground(new java.awt.Color(51, 51, 51));

    title.setFont(new java.awt.Font("Tahoma", 1, 14)); // NOI18N
    title.setForeground(new java.awt.Color(153, 255, 204));
    title.setText("Student Grades");

    firstLabel.setForeground(new java.awt.Color(153, 255, 204));
    firstLabel.setText("First Name:");

    secondLabel.setForeground(new java.awt.Color(153, 255, 204));
    secondLabel.setText("Last Name:");

    firstInput.setBackground(new java.awt.Color(204, 204, 204));

    secondInput.setBackground(new java.awt.Color(204, 204, 204));

    test1.setForeground(new java.awt.Color(153, 255, 204));
    test1.setText("Test 1");

    test2.setForeground(new java.awt.Color(153, 255, 204));
    test2.setText("Test 2");

    test3.setForeground(new java.awt.Color(153, 255, 204));
    test3.setText("Test 3");

    test4.setForeground(new java.awt.Color(153, 255, 204));
    test4.setText("Test 4");

    test1Input.setBackground(new java.awt.Color(204, 204, 204));

    test2Input.setBackground(new java.awt.Color(204, 204, 204));

    test3Input.setBackground(new java.awt.Color(204, 204, 204));

    test4Input.setBackground(new java.awt.Color(204, 204, 204));

    addButton.setBackground(new java.awt.Color(153, 153, 153));
    addButton.setForeground(new java.awt.Color(153, 255, 204));
    addButton.setText("Add");
    addButton.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            addButtonActionPerformed(evt);
        }
    });

    listButton.setBackground(new java.awt.Color(153, 153, 153));
    listButton.setForeground(new java.awt.Color(153, 255, 204));
    listButton.setText("List");
    listButton.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            listButtonActionPerformed(evt);
        }
    });

    stundentAvButton.setBackground(new java.awt.Color(153, 153, 153));
    stundentAvButton.setForeground(new java.awt.Color(153, 255, 204));
    stundentAvButton.setText("Student Average");

    courseAvButton.setBackground(new java.awt.Color(153, 153, 153));
    courseAvButton.setForeground(new java.awt.Color(153, 255, 204));
    courseAvButton.setText("Course Average");

    exit.setBackground(new java.awt.Color(153, 153, 153));
    exit.setForeground(new java.awt.Color(153, 255, 204));
    exit.setText("Exit");
    exit.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            exitActionPerformed(evt);
        }
    });

    jScrollPane1.setViewportView(outBox);

    javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
    jPanel1.setLayout(jPanel1Layout);
    jPanel1Layout.setHorizontalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(jPanel1Layout.createSequentialGroup()
            .addContainerGap()
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(jPanel1Layout.createSequentialGroup()
                    .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addComponent(test3)
                        .addGroup(jPanel1Layout.createSequentialGroup()
                            .addComponent(firstLabel)
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                            .addComponent(firstInput, javax.swing.GroupLayout.PREFERRED_SIZE, 95, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGroup(jPanel1Layout.createSequentialGroup()
                            .addComponent(test1)
                            .addGap(18, 18, 18)
                            .addComponent(test1Input, javax.swing.GroupLayout.PREFERRED_SIZE, 33, javax.swing.GroupLayout.PREFERRED_SIZE)))
                    .addGap(18, 18, Short.MAX_VALUE)
                    .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                        .addGroup(jPanel1Layout.createSequentialGroup()
                            .addComponent(listButton)
                            .addGap(18, 18, 18)
                            .addComponent(courseAvButton, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                        .addGroup(jPanel1Layout.createSequentialGroup()
                            .addComponent(addButton)
                            .addGap(18, 18, 18)
                            .addComponent(stundentAvButton))
                        .addGroup(jPanel1Layout.createSequentialGroup()
                            .addGap(10, 10, 10)
                            .addComponent(secondLabel)
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                            .addComponent(secondInput, javax.swing.GroupLayout.PREFERRED_SIZE, 95, javax.swing.GroupLayout.PREFERRED_SIZE))))
                .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                    .addGap(0, 0, Short.MAX_VALUE)
                    .addComponent(title)
                    .addGap(99, 99, 99))
                .addGroup(jPanel1Layout.createSequentialGroup()
                    .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                        .addComponent(test3Input, javax.swing.GroupLayout.PREFERRED_SIZE, 33, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGroup(jPanel1Layout.createSequentialGroup()
                            .addComponent(test2)
                            .addGap(18, 18, 18)
                            .addComponent(test2Input, javax.swing.GroupLayout.PREFERRED_SIZE, 33, javax.swing.GroupLayout.PREFERRED_SIZE)))
                    .addGap(0, 0, Short.MAX_VALUE))
                .addGroup(jPanel1Layout.createSequentialGroup()
                    .addComponent(test4)
                    .addGap(18, 18, 18)
                    .addComponent(test4Input, javax.swing.GroupLayout.PREFERRED_SIZE, 33, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGap(10, 10, 10)
                    .addComponent(jScrollPane1)))
            .addGap(52, 52, 52))
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
            .addGap(0, 0, Short.MAX_VALUE)
            .addComponent(exit))
    );
    jPanel1Layout.setVerticalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(jPanel1Layout.createSequentialGroup()
            .addContainerGap()
            .addComponent(title)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(firstLabel)
                .addComponent(secondLabel)
                .addComponent(firstInput, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(secondInput, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addGap(18, 18, 18)
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(test1)
                .addComponent(addButton)
                .addComponent(stundentAvButton)
                .addComponent(test1Input, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(test2)
                .addComponent(test2Input, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(test3)
                .addComponent(listButton)
                .addComponent(courseAvButton)
                .addComponent(test3Input, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(jPanel1Layout.createSequentialGroup()
                    .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                        .addComponent(test4)
                        .addComponent(test4Input, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 103, Short.MAX_VALUE)
                    .addComponent(exit))
                .addComponent(jScrollPane1)))
    );

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
    );

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

private void addButtonActionPerformed(java.awt.event.ActionEvent evt) {                                          

   String studentNames = (firstInput.getText() + secondInput.getText());

    students[next][0] = studentNames;
    students[next][1] = test1Input.getText();
    students[next][2] = test2Input.getText();
    students[next][3] = test3Input.getText();
    students[next][4] = test4Input.getText();
    next++;


}                                         

private void listButtonActionPerformed(java.awt.event.ActionEvent evt) {                                           
    StringBuilder sb = new StringBuilder();
    for (int row = 0; row <= 15; row++) {
        for (int col = 0; col <= 4; col++) {
            sb.append(students[row][col] + " ");
        }
        sb.append(System.lineSeparator());
    }
    outBox.setText(sb.toString());
}                                          

private void exitActionPerformed(java.awt.event.ActionEvent evt) {                                     
    System.exit(0);
}                                    

/**
 * @param args the command line arguments
 */
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(UI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(UI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(UI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(UI.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 UI().setVisible(true);
        }
    });
}

// Variables declaration - do not modify                     
private javax.swing.JButton addButton;
private javax.swing.JButton courseAvButton;
private javax.swing.JButton exit;
private javax.swing.JTextField firstInput;
private javax.swing.JLabel firstLabel;
private javax.swing.JPanel jPanel1;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JButton listButton;
private javax.swing.JTextPane outBox;
private javax.swing.JTextField secondInput;
private javax.swing.JLabel secondLabel;
private javax.swing.JButton stundentAvButton;
private javax.swing.JLabel test1;
private javax.swing.JTextField test1Input;
private javax.swing.JLabel test2;
private javax.swing.JTextField test2Input;
private javax.swing.JLabel test3;
private javax.swing.JTextField test3Input;
private javax.swing.JLabel test4;
private javax.swing.JTextField test4Input;
private javax.swing.JLabel title;
// End of variables declaration                   

}

Answer 1

您不断覆盖输出框中的文本。一种更好的方法是将文本累积在 StringBuilder 中，然后将其设置到输出框:

private void listButoonActionPerformed(java.awt.event.ActionEvent evt) {
    StringBuilder sb = new StringBuilder();
    for (int row = 0; row <= 15; row++) {
        for (int col = 0; col <= 4; col++) {
            sb.append(students[row][col]).append(" ");

        }
        sb.append(System.lineSeparator());
    }
    outBox.setText(sb.toString());
}