Change JCombobox item color when choose by keyboard or mouse

Question

Normally when we choose the items in jCombobox by mouse or keyborad up and down keys, the background of item will be 'blue' color.

I want to change the color from blue to any other color something like follows.

Answer 1

Another option is to use JList#setSelectionBackground(Color).

import java.awt.*;
import javax.accessibility.AccessibleContext;
import javax.swing.*;
import javax.swing.plaf.basic.BasicComboPopup;

public class ComboTest {
  public JComponent makeUI() {
    // TEST:
    // UIManager.put("ComboBox.selectionBackground", Color.GREEN);
    // UIManager.put("ComboBox.selectionForeground", Color.CYAN);

    String[] model = {"Male", "Female"};

    JComboBox<String> combo1 = new JComboBox<>(model);
    AccessibleContext ac = combo1.getAccessibleContext();
    BasicComboPopup pop = (BasicComboPopup) ac.getAccessibleChild(0);
    JList list = pop.getList();
    list.setSelectionForeground(Color.WHITE);
    list.setSelectionBackground(Color.ORANGE);

    // ???: The focus border of the JComboBox is not drawn.
    JComboBox<String> combo2 = new JComboBox<>(model);
    combo2.setRenderer(new DefaultListCellRenderer() {
      @Override public Component getListCellRendererComponent(
          JList list, Object value, int index,
          boolean isSelected, boolean hasFocus) {
        JLabel l = (JLabel) super.getListCellRendererComponent(
            list, value, index, isSelected, hasFocus);
        if (isSelected) {
          l.setForeground(Color.WHITE);
          l.setBackground(Color.ORANGE);
        } else {
          l.setForeground(Color.BLACK);
          l.setBackground(Color.WHITE);
        }
        return l;
      }
    });

//     // TEST:
//     JComboBox<String> combo3 = new JComboBox<>(model);
//     combo3.setRenderer(new DefaultListCellRenderer() {
//       @Override public Component getListCellRendererComponent(
//           JList list, Object value, int index,
//           boolean isSelected, boolean hasFocus) {
//         list.setSelectionForeground(Color.WHITE);
//         list.setSelectionBackground(Color.ORANGE);
//         return super.getListCellRendererComponent(
//             list, value, index, isSelected, hasFocus);
//       }
//     });

    JPanel box = new JPanel(new GridLayout(0, 1, 10, 10));
    box.add(combo1);
    box.add(combo2);
//     box.add(combo3);

    JPanel p = new JPanel(new BorderLayout());
    p.setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
    p.add(box, BorderLayout.NORTH);
    return p;
  }
  public static void main(String[] args) {
    EventQueue.invokeLater(() -> {
      try {
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        // UIManager.setLookAndFeel("javax.swing.plaf.nimbus.NimbusLookAndFeel");
      } catch (Exception e) {
        e.printStackTrace();
      }
      JFrame f = new JFrame();
      f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
      f.getContentPane().add(new ComboTest().makeUI());
      f.setSize(320, 240);
      f.setLocationRelativeTo(null);
      f.setVisible(true);
    });
  }
}