下面的示例演示了如何在基于swing的应用程序中向组合框添加分隔符。
使用以下API -
JComboBox()- 创建标准组合框。JCheckBox.setRenderer(renderer);- 设置处理JSeparator的自定义渲染器。ListCellRenderer- 为组合框创建自定义单元格渲染器。
示例
package com.yiibai.swingdemo;
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.LayoutManager;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JSeparator;
import javax.swing.ListCellRenderer;
public class SwingTester {
public static void main(String[] args) {
createWindow();
}
private static void createWindow() {
JFrame frame = new JFrame("Swing组合框中添加分隔符");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
createUI(frame);
frame.setSize(560, 200);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private static void createUI(final JFrame frame){
JPanel panel = new JPanel();
LayoutManager layout = new FlowLayout();
panel.setLayout(layout);
Object[] numbers = {"Yiibai.com", "Kaops.com", "Viibm.com",
new JSeparator(JSeparator.HORIZONTAL), "Baidu.com", "Google.com"};
JComboBox<Object> comboBox = new JComboBox<>(numbers);
comboBox.setSelectedIndex(1);
ComboBoxRenderer renderer= new ComboBoxRenderer();
renderer.setPreferredSize(new Dimension(100, 20));
comboBox.setRenderer(renderer);
comboBox.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
JComboBox combo = (JComboBox)e.getSource();
JOptionPane.showMessageDialog(frame,combo.getSelectedItem());
}
});
panel.add(comboBox);
frame.getContentPane().add(panel, BorderLayout.CENTER);
}
}
class ComboBoxRenderer extends JLabel implements ListCellRenderer<Object> {
public Component getListCellRendererComponent(JList<? extends Object> list,
Object value, int index, boolean isSelected, boolean cellHasFocus) {
if(value instanceof JSeparator){
return (Component)value;
}else{
setText(value.toString());
}
return this;
}
}
执行上面示例代码，得到以下结果：
