java - JComboBox 的行为与 JTextField 不同。我怎样才能让它看起来相似？

Question

我有以下组合框，我可以在其中创建带有项目等的组合框，但外观与 JTextField 不同。我怎样才能使 JCombobox 看起来像 JTextField？

我的组合框.java:

import java.awt.Color;
import javax.swing.*;
import javax.swing.border.Border;
import javax.swing.border.LineBorder;
import javax.swing.plaf.basic.BasicComboBoxUI;

public class MyComboBox extends JComboBox {
  public MyComboBox(String[] name) {
    Border border = BorderFactory.createEmptyBorder(11, 11, 11, 11);
    JComboBox cb = new JComboBox(name);
    cb.setUI(new BasicComboBoxUI() {
        @Override
        protected JButton createArrowButton() {
            return new JButton() {
                    @Override
                    public int getWidth() {
                            return 0;
                    }
            };
        }
    });

    setModel(cb.getModel());    
    setOpaque(false);
    setBorder(new LineBorder(Color.black, 1, true));
    //setBackground(Color.white);
    setVisible(true); 


  }
//  public void paintComponent(Graphics g) {
//      super.paintComponent(g);                
//      g.setColor(new Color(red, green, blue) );
//      g.fillOval(125, 125, 50, 50);
//  }  
}

Answer 1

• 最重要的是可以使用 Look and Feels

• JComboBox有两种状态，JComboBox可以是Editable和Non_Editable(默认)

• 没有CustomUI(如@aterai 的示例)，但Look and Feel 敏感，仅适用于Metal Look and Feel

import java.awt.*;
import java.util.Vector;
import javax.swing.*;
import javax.swing.UIManager;
import javax.swing.plaf.ColorUIResource;
import javax.swing.plaf.metal.MetalComboBoxButton;

public class MyComboBox {

    private Vector<String> listSomeString = new Vector<String>();
    private JComboBox someComboBox = new JComboBox(listSomeString);
    private JComboBox editableComboBox = new JComboBox(listSomeString);
    private JComboBox non_EditableComboBox = new JComboBox(listSomeString);
    private JFrame frame;

    public MyComboBox() {
        listSomeString.add("-");
        listSomeString.add("Snowboarding");
        listSomeString.add("Rowing");
        listSomeString.add("Knitting");
        listSomeString.add("Speed reading");
//
        someComboBox.setPrototypeDisplayValue("xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx");
        someComboBox.setFont(new Font("Serif", Font.BOLD, 16));
        someComboBox.setEditable(true);
        someComboBox.getEditor().getEditorComponent().setBackground(Color.YELLOW);
        ((JTextField) someComboBox.getEditor().getEditorComponent()).setBackground(Color.YELLOW);
//        
        editableComboBox.setPrototypeDisplayValue("xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx");
        editableComboBox.setFont(new Font("Serif", Font.BOLD, 16));
        editableComboBox.setEditable(true);
        JTextField text = ((JTextField) editableComboBox.getEditor().getEditorComponent());
        text.setBackground(Color.YELLOW);
        JComboBox coloredArrowsCombo = editableComboBox;
        Component[] comp = coloredArrowsCombo.getComponents();
        for (int i = 0; i < comp.length; i++) {
            if (comp[i] instanceof MetalComboBoxButton) {
                MetalComboBoxButton coloredArrowsButton = (MetalComboBoxButton) comp[i];
                coloredArrowsButton.setBackground(null);
                break;
            }
        }
//        
        non_EditableComboBox.setPrototypeDisplayValue("xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx");
        non_EditableComboBox.setFont(new Font("Serif", Font.BOLD, 16));
//
        frame = new JFrame();
        frame.setLayout(new GridLayout(0, 1, 10, 10));
        frame.add(someComboBox);
        frame.add(editableComboBox);
        frame.add(non_EditableComboBox);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocation(100, 100);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        UIManager.put("ComboBox.background", new ColorUIResource(Color.yellow));
        UIManager.put("JTextField.background", new ColorUIResource(Color.yellow));
        UIManager.put("ComboBox.selectionBackground", new ColorUIResource(Color.magenta));
        UIManager.put("ComboBox.selectionForeground", new ColorUIResource(Color.blue));
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                MyComboBox aCTF = new MyComboBox();
            }
        });
    }
}