Java如何添加项目和从JComboBox删除项目？
本示例演示如何使用insertItemAt(Objecto,intindex)andaddItem(Objecto)方法将项目添加到组合框列表中的特定位置或列表的末尾。在代码中，我们还将学习如何使用的removeItemAt(intindex)方法和removeAllItems()方法从列表中删除一项或所有项JComboBox。
package org.nhooo.example.swing;
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class ComboBoxAddRemoveItem extends JFrame {
public ComboBoxAddRemoveItem() {
initialize();
}
private void initialize() {
setSize(300, 300);
setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
setLayout(new FlowLayout(FlowLayout.LEFT));
String[] items = new String[] {"Two", "Four", "Six", "Eight"};
final JComboBox comboBox = new JComboBox(items);
getContentPane().add(comboBox);
JButton button1 = new JButton("Add One");
button1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
// 在列表的开头添加项目“One”
comboBox.insertItemAt("One", 0);
}
});
JButton button2 = new JButton("Add Five and Nine");
button2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
comboBox.insertItemAt("Five", 3);
comboBox.addItem("Nine");
}
});
getContentPane().add(button1);
getContentPane().add(button2);
JButton remove1 = new JButton("Remove Eight and Last");
remove1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
// 从列表中删除八个项目和最后一个项目。
comboBox.removeItemAt(5);
comboBox.removeItemAt(comboBox.getItemCount() - 1);
}
});
JButton remove2 = new JButton("Remove All");
remove2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
comboBox.removeAllItems();
}
});
getContentPane().add(remove1);
getContentPane().add(remove2);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new ComboBoxAddRemoveItem().setVisible(true);
}
});
}
}