使用JComboBox而不是JButton填充JTable

Question

我只是Java的初學者，如果您能幫助我，我會很高興，我這里有一個JTable，它使用JButton填充了數據庫中的數據。 我有3張桌子，分別是學生 ， 老師和導演 。 使用3個JButton（每個表一個）查看JTable中的那些字段，一切都工作正常。 但是每次我單擊另一個JButton時，都不會清除JTable，而是將數據添加到JTable的現有信息中。

現在，我要做的是將3個JButton替換為JComboBox，其中要選擇的選項是表名稱，並在JTable中顯示其內容。 我真的不知道如何做到這一點。 希望您能對此提供幫助，並感謝您的投入。

謝謝

以下是我使用的代碼。 我還包括一些標題。

import java.sql.*;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.DefaultComboBoxModel;
import javax.swing.table.DefaultTableModel;

public class tests extends javax.swing.JFrame {

/**
 * Creates new form tests
 */
public tests() {
    initComponents();
}

@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {

    jScrollPane1 = new javax.swing.JScrollPane();
    dataTable = new javax.swing.JTable();
    students = new javax.swing.JButton();
    teachers = new javax.swing.JButton();
    directors = new javax.swing.JButton();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    dataTable.setModel(new javax.swing.table.DefaultTableModel(
        new Object [][] {

        },
        new String [] {
            "ID", "Name", "Surname", "Age"
        }
    ));
    jScrollPane1.setViewportView(dataTable);

    students.setText("Students");
    students.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            studentsActionPerformed(evt);
        }
    });

    teachers.setText("Teachers");
    teachers.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            teachersActionPerformed(evt);
        }
    });

    directors.setText("Directors");
    directors.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            directorsActionPerformed(evt);
        }
    });

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addContainerGap()
            .addComponent(students)
            .addGap(57, 57, 57)
            .addComponent(teachers)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 66, Short.MAX_VALUE)
            .addComponent(directors)
            .addGap(40, 40, 40))
        .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 0, Short.MAX_VALUE)
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
            .addContainerGap()
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(students)
                .addComponent(teachers)
                .addComponent(directors))
            .addGap(18, 18, 18)
            .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 274, Short.MAX_VALUE))
    );

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

private void studentsActionPerformed(java.awt.event.ActionEvent evt) {
    DefaultTableModel model = (DefaultTableModel) dataTable.getModel();
    String sql = "select * from students";
    try {
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(tests.class.getName()).log(Level.SEVERE, null, ex);
        }
        Connection connect = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/datavisibility","root","");
        Statement statmnt = connect.createStatement();
        ResultSet rslt = statmnt.executeQuery(sql);
        while(rslt.next()){
            String id = rslt.getString("ID");
            String name = rslt.getString("Name");
            String surname = rslt.getString("Surname");
            String age = rslt.getString("Age");
            model.addRow(new Object[]{id,name,surname,age});
        }
    } catch(SQLException e){
        e.printStackTrace();
    }
}

private void teachersActionPerformed(java.awt.event.ActionEvent evt) {
    DefaultTableModel model = (DefaultTableModel) dataTable.getModel();
    String sql = "select * from teachers";
    try {
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(tests.class.getName()).log(Level.SEVERE, null, ex);
        }
        Connection connect = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/datavisibility","root","");
        Statement statmnt = connect.createStatement();
        ResultSet rslt = statmnt.executeQuery(sql);
        while(rslt.next()){
            String id = rslt.getString("ID");
            String name = rslt.getString("Name");
            String surname = rslt.getString("Surname");
            String age = rslt.getString("Age");
            model.addRow(new Object[]{id,name,surname,age});
        }
    } catch(SQLException e){
        e.printStackTrace();
    }
}

private void directorsActionPerformed(java.awt.event.ActionEvent evt) {
    DefaultTableModel model = (DefaultTableModel) dataTable.getModel();
    String sql = "select * from directors";
    try {
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(tests.class.getName()).log(Level.SEVERE, null, ex);
        }
        Connection connect = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/datavisibility","root","");
        Statement statmnt = connect.createStatement();
        ResultSet rslt = statmnt.executeQuery(sql);
        while(rslt.next()){
            String id = rslt.getString("ID");
            String name = rslt.getString("Name");
            String surname = rslt.getString("Surname");
            String age = rslt.getString("Age");
            model.addRow(new Object[]{id,name,surname,age});
        }
    } catch(SQLException e){
        e.printStackTrace();
    }
}

/**
 * @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(tests.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(tests.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(tests.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(tests.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 tests().setVisible(true);
        }
    });
}
// Variables declaration - do not modify
private javax.swing.JTable dataTable;
private javax.swing.JButton directors;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JButton students;
private javax.swing.JButton teachers;
// End of variables declaration
}

在此處查看標題。

提前致謝。

Answer 1

只需添加JComboBox而不是像這樣的JButton，

String[] items = {"students", "teachers", "directors"};
JComboBox cb = new JComboBox(items);
cb.setEditable(true);

像這樣將Listener類添加到組合框，

ActionListener actionListener = new ActionListener() {
  public void actionPerformed(ActionEvent actionEvent) {
    //System.out.println("Selected: " + cb.getSelectedItem());
     if(cb.getSelectedItem() == "student"){

       //Perform the action for student

     } 

      //Repeat this for all items

  }
};
cb.addActionListener(actionListener);

這將滿足您的期望。

Answer 2

您需要做的就是為您的JCombobox添加一個ActionListener。 在actionListener中，根據getSelectedItem（）返回的值更改表中的數據。

如果需要更多幫助，請嘗試編寫並發布代碼