如何在JComboBox的箭头图标附近添加图标

Question

我想创建类似于Firefox的URL文本框的JComboBox控件。 有谁知道如何自定义JComboBox的文本字段。 我想在JComboBox的箭头按钮附近的ALIGN.HORIZONTAL_RIGHT上添加一些图标

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感谢您的详细解释。 实际上，我将结合DefaultListCellRenderer并将图标添加到组合框中，如以下代码所示

import java.awt.Dimension;
import java.awt.Insets;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;

public class Main extends JFrame {
    public Main() {
        // Create icon "C"
        JButton jb = new JButton("C");
        jb.setMargin(new Insets(0, 0, 0, 0));
        jb.setBounds(245, 2, 18, 18);

        // Create combo box
        String[] languages = new String[]{"Java", "C#", "PHP"};
        JComboBox jc = new JComboBox(languages);
        // jc.setEditable(true);
        jc.add(jb);

        getContentPane().add(jc);

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(new Dimension(300, 58));
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        final Main main = new Main();
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                main.setVisible(true);
            }
        });
    }
}

但是当我放jc.setEditable(true) ； 组合编辑器隐藏了我的图标。 我在想另一种模拟Firefox棒的方法。 您对此有什么想法吗？

Answer 1

要更改组件的渲染方式，通常需要使用所谓的Renderer 。

对于combobox，请查看如何创建自定义的combobox渲染器 。 乍一看，但对于您而言，只需配置DefaultListCellRenderer即可，因为您可以设置JLabel属性以将文本放置在图像上。 如果不是，则从其扩展。

还要记住，您必须设置一个包含图标的模型，以便组合框渲染器可以获取它-可能还要根据您的数据对象做一个自定义的ComboBoxModel 。

Answer 2

这是演示它的完整示例：

package com.demo.combo.icon;



import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.HashMap;
import java.util.Map;

import javax.swing.DefaultListCellRenderer;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;


public class ShowConboWithIcons extends JFrame {

private static final long serialVersionUID = 1L;

private static final ImageIcon INFO_ICON  = new ImageIcon("info.png");
private static final ImageIcon NONE_ICON  = new ImageIcon("none.png");
public final String NONE_STR = "None";
private final String INFO_STR = "Info";

private JComboBox comboBox;
private JPanel    topPanel;

private String[] str_arr = null; 


public ShowConboWithIcons(String[] str_arr) {
    this.str_arr = str_arr;     
}


public void createGUI(){

    setMinimumSize(new Dimension(100,100));
    setTitle("Demo");
    setLocation(200, 200);

    topPanel = new JPanel();
    getContentPane().add(topPanel, BorderLayout.CENTER);

    Map<Object, Icon> icons = new HashMap<Object, Icon>(); 

    icons.put(NONE_STR, NONE_ICON); 
    icons.put(INFO_STR, INFO_ICON); 

    comboBox = new JComboBox();
    comboBox.setRenderer(new IconListRenderer(icons));
    comboBox.addItem("None");

    for(String val : str_arr){
        comboBox.addItem(val);
    }

    topPanel.add(comboBox);

    super.addWindowListener(new WindowAdapter() {           
        public void windowClosing(WindowEvent e) {              
            dispose();          
        }           
    }); 
}

public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException, UnsupportedLookAndFeelException {

    UIManager.setLookAndFeel( "com.sun.java.swing.plaf.windows.WindowsLookAndFeel" );   

    String[] str_arr = {"A", "B", "C", "D", "E"};

    ShowConboWithIcons T = new ShowConboWithIcons(str_arr);
    T.createGUI();
    T.setVisible(true);        
}


class IconListRenderer extends DefaultListCellRenderer{ 
    private static final long serialVersionUID = 1L;
    private Map<Object, Icon> icons = null; 

    public IconListRenderer(Map<Object, Icon> icons){ 
        this.icons = icons; 
    } 

    @Override
    public Component getListCellRendererComponent(JList list, Object value, int index,boolean isSelected, boolean cellHasFocus)
    { 
        JLabel label = (JLabel) super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus); 

        // Get icon to use for the list item value 
        Icon icon = icons.get(value); 

        if(!value.toString().equals(NONE_STR)){
            icon = icons.get(INFO_STR);
        }

        // Set icon to display for value 
        label.setIcon(icon); 
        return label; 
    } 
}
}

预习：