Question

我有以下组合框，我可以使用项目等创建我的组合框，但外观与JTextField不同。如何使JCombobox看起来像JTextField一样？

enter image description here

MyComboBox.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（例如@aterai），但Look and Feel敏感，仅适用于Metal Look and Feel

enter image description here

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();
            }
        });
    }
}

Answer 2

我猜你的意思是RoundedCornerBorder：

import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.plaf.basic.*;

public class RoundedComboBoxTest {
  public JComponent makeUI() {
    UIManager.put("Panel.background", Color.GRAY);
    UIManager.put("ComboBox.foreground", Color.BLACK);
    UIManager.put("ComboBox.background", Color.GRAY);
    UIManager.put("ComboBox.selectionForeground", Color.WHITE);
    UIManager.put("ComboBox.selectionBackground", Color.GRAY);
    UIManager.put("ComboBox.buttonDarkShadow", Color.BLACK);
    UIManager.put("ComboBox.border", new RoundedCornerBorder());

    DefaultComboBoxModel<String> m = new DefaultComboBoxModel<>();
    m.addElement("1234");
    m.addElement("5555555555555555555555");
    m.addElement("6789000000000");
    JComboBox<String> combo = new JComboBox<>(m);
    combo.setUI(new BasicComboBoxUI() {
      @Override protected JButton createArrowButton() {
        JButton b = super.createArrowButton();
        b.setContentAreaFilled(false);
        b.setBackground(Color.GRAY);
        b.setBorder(BorderFactory.createEmptyBorder());
        return b;
      }
    });
    Object o = combo.getAccessibleContext().getAccessibleChild(0);
    ((JComponent)o).setBorder(
        BorderFactory.createMatteBorder(0,1,1,1,Color.BLACK));
    JPanel p = new JPanel(new BorderLayout());
    p.add(combo, BorderLayout.NORTH);
    p.setOpaque(true);
    p.setBackground(Color.GRAY);
    p.setBorder(BorderFactory.createEmptyBorder(15,15,15,15));
    return p;
  }
  public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
      @Override public void run() {
        createAndShowGUI();
      }
    });
  }
  public static void createAndShowGUI() {
    JFrame f = new JFrame();
    f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    f.getContentPane().add(new RoundedComboBoxTest().makeUI());
    f.setSize(320, 240);
    f.setLocationRelativeTo(null);
    f.setVisible(true);
  }
}
class RoundedCornerBorder extends AbstractBorder {
  @Override public void paintBorder(
      Component c, Graphics g, int x, int y, int width, int height) {
    Graphics2D g2 = (Graphics2D)g.create();
    g2.setRenderingHint(
        RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
    int r = 12;
    Area round = new Area(
        new RoundRectangle2D.Float(x, y, width-1, height-1, r, r));
    Rectangle b = round.getBounds();
    b.setBounds(b.x, b.y + r, b.width, b.height - r);
    round.add(new Area(b));

    Container parent = c.getParent();
    if(parent!=null) {
      g2.setColor(parent.getBackground());
      Area corner = new Area(new Rectangle2D.Float(x, y, width, height));
      corner.subtract(round);
      g2.fill(corner);
    }
    g2.setColor(Color.BLACK);
    g2.draw(round);
    g2.dispose();
  }
  @Override public Insets getBorderInsets(Component c) {
    return new Insets(4, 8, 4, 8);
  }
  @Override public Insets getBorderInsets(Component c, Insets insets) {
    insets.left = insets.right = 8;
    insets.top = insets.bottom = 4;
    return insets;
  }
}

Answer 3

您必须定义自己的自定义渲染器，请查看此tutorial，了解如何定义它。

您还可以在MyComboBox.java中设置背景和前景，但这不会对所选项目前景，背景产生影响。

JComboBox的行为与JTextField不同。我怎么能看起来相似？

3 个答案: