如何在 Java 中设置 JComboBox 项目的边框?
awtjavaobject oriented programmingprogrammingswing
JComboBox 是 JComponent 类的子类，它是 text 字段和 下拉列表的组合，用户可以从中选择一个值。当用户对组合框执行操作时，JComboBox 可以生成 ActionListener、ChangeListener 和 ItemListener 接口。我们可以通过呈现 JComboBox (扩展 DefaultListCellRenderer 类并需要覆盖 getListCellRendererComponent() 方法)来设置 JComboBox 项目的边框。
语法
public Component getListCellRendererComponent(JList<?> list, Object value, int index, boolean isSelected, boolean cellHasFocus)
示例
import java.awt.*;
import javax.swing.*;
public class JComboBoxTest extends JFrame {
public JComboBoxTest() {
setTitle("JComboBox Test");
String[] cities = {"Hyderabad", "Mumbai", "Pune", "Bangalore", "Chennai", "Coimbatore"};
JComboBox jcb = new JComboBox(cities);
jcb.setRenderer(new CustomComboBoxRenderer());
add(jcb, BorderLayout.NORTH);
setSize(400, 300);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
setVisible(true);
}
class CustomComboBoxRenderer extends DefaultListCellRenderer {
public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
JLabel lbl = (JLabel)super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
lbl.setBorder(BorderFactory.createEmptyBorder(7, 7, 7, 7));
lbl.setBackground(Color.lightGray);
return lbl;
}
}
public static void main(String[] args) {
new JComboBoxTest();
}
}
输出
