JComboBox更改下拉弹出窗口

Question

基本上是一个弹出窗口，用于显示JComboBox下面的派生JTextField，如何从下方方向更改JComboBox的弹出窗口的方向，并在顶部/覆盖它显示JComboBox的弹出窗口

编辑：基本JComboBox的代码示例

import java.awt.Dimension;
import javax.swing.*;
import javax.swing.plaf.basic.BasicComboBoxRenderer;

public class HighRowCombo {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new HighRowCombo().makeUI();
            }
        });
    }

    public void makeUI() {
        Object[] data = {"One", "Two with text", "Three with long text, with long text,with long text "};
        JComboBox comboBox = new JComboBox(data);
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null);
        frame.add(comboBox);
        frame.pack();
        BasicComboBoxRenderer renderer = (BasicComboBoxRenderer) comboBox.getRenderer();
        Dimension size = renderer.getPreferredSize();
        size.height += 50;
        renderer.setPreferredSize(size);
        frame.setVisible(true);
    }
}

编辑第二段。 MacOX的代码

import java.awt.*;
import javax.swing.*;

public class TestHighRow {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
                } catch (Exception e) {
                    e.printStackTrace();
                }
                new TestHighRow().makeUI();
            }
        });
    }

    public void makeUI() {
        Object[] data = {"One", "Two", "Three"};
        JComboBox comboBox = new JComboBox(data);
        comboBox.setPreferredSize(comboBox.getPreferredSize());
        comboBox.setRenderer(new HighRowRenderer(comboBox.getRenderer()));
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.getContentPane().add(comboBox);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static class HighRowRenderer implements ListCellRenderer {

        private final ListCellRenderer delegate;
        private int height = -1;

        public HighRowRenderer(ListCellRenderer delegate) {
            this.delegate = delegate;
        }

        @Override
        public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
            Component component = delegate.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
            Dimension size = component.getPreferredSize();
            if (height == -1) {
                height = size.height + 50;
            }
            size.height = height;
            component.setPreferredSize(size);
            if (component instanceof JLabel) {
                ((JLabel) component).setHorizontalTextPosition(JLabel.CENTER);
            }
            return component;
        }
    }
}

- mKorbel

Answer 1

尝试使用组合框弹出窗口中的setPopupAbove()方法。

- camickr

Answer 2

在我的系统中，如果 JComboBox 靠近屏幕底部且没有足够的空间向下展开，则它会向上打开。(这是你的意思吗？) 鉴于这个事实，我怀疑改变已定义的行为不会很容易。

- Andrew Thompson

---

我为状态栏功能使用了(JPanel, BorderLayout.SOUTH)，其中包含一个JComboBox，我“想要”将JComboBox的弹出窗口嵌入到JFrame中 :-) - mKorbel

Answer 3

在Mac OS X上，我收到了以下异常。 显然，com.apple.laf.AquaComboBoxRenderer不是BasicComboBoxRenderer的子类。

补充说明：ClassCastException消失了，并且下面显示了“EDIT 2nd. Code for MacOX”的屏幕截图： 在AWT-EventQueue-0线程中发生异常java.lang.ClassCastException： com.apple.laf.AquaComboBoxRenderer无法转换为javax.swing.plaf.basic.BasicComboBoxRenderer 在HighRowCombo.makeUI（HighRowCombo.java:26）处 在HighRowCombo $1.run（HighRowCombo.java:13）处 在java.awt.event.InvocationEvent.dispatch（InvocationEvent.java:209）处 在java.awt.EventQueue.dispatchEventImpl（EventQueue.java:678）处 在java.awt.EventQueue.access＄000（EventQueue.java:86）处 在java.awt.EventQueue $1.run（EventQueue.java:639）处 在java.awt.EventQueue $1.run（EventQueue.java:637）处 在java.security.AccessController.doPrivileged（Native Method）处 在java.security.AccessControlContext$1.doIntersectionPrivilege（AccessControlContext.java:87）处 在java.awt.EventQueue.dispatchEvent（EventQueue.java:648）处 在java.awt.EventDispatchThread.pumpOneEventForFilters（EventDispatchThread.java:296）处 在java.awt.EventDispatchThread.pumpEventsForFilter（EventDispatchThread.java:211）处 在java.awt.EventDispatchThread.pumpEventsForHierarchy（EventDispatchThread.java:201）处 在java.awt.EventDispatchThread.pumpEvents（EventDispatchThread.java:196）处 在java.awt.EventDispatchThread.pumpEvents（EventDispatchThread.java:188）处 在java.awt.EventDispatchThread.run（EventDispatchThread.java:122）处

- trashgod

---

（叹气）Mac。- 敢于与众不同。 ;) - Andrew Thompson

据我所知，MetalLookAndFeel始终可用。有时我会使用在这里看到的方法来“借用”另一个L&F中的元素，例如图标。 - trashgod

移除并替换为ListCellRenderer。 - mKorbel

@mKorbel：第二次编辑看起来不错；我已经添加了一张截图，如上所示。 - trashgod

Answer 4

package com.example.swing;

import javax.swing.JList;
import javax.swing.ListCellRenderer;
import java.awt.Component;
import java.awt.Dimension;

public class PaddingListCellRenderer<Type> implements ListCellRenderer<Type> {
    private final ListCellRenderer original;
    private final int hpadding;
    private final int vpadding;

    public PaddingListCellRenderer(ListCellRenderer original, int hpadding, int vpadding) {
        this.original = original;
        this.hpadding = hpadding;
        this.vpadding = vpadding;
    }

    @Override
    @SuppressWarnings("unchecked")
    public Component getListCellRendererComponent(JList<? extends Type> list, Type value, int index, boolean isSelected, boolean cellHasFocus) {
        final Component component = original.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
        component.setPreferredSize(null);
        final Dimension pref = component.getPreferredSize();
        component.setPreferredSize(new Dimension(pref.width + 2 * hpadding, pref.height + 2 * vpadding));
        return component;
    }
}

- ivan.a.bovin