Question

我已阅读/试过这些帖子，但这没有帮助：

我需要的是ListCellRenderer，它返回一个左侧带有图标的面板和右侧的动态长度文本（就像在任何论坛中一样：左侧是用户头像，右侧是帖子）文本）。我知道的文本 NOT ，所以我无法设置固定的单元格高度。此外，文本长度不同于列表单元格到列表单元格。因此，每个列表单元格都需要自己的高度，具体取决于文本的长度。实际上是一个非常常见的布局...但不适用于Swing。单元格高度不会根据文本长度扩展。

我已经阅读了JList中几乎所有关于动态单元格高度和多行文本的帖子，但找不到解决方案。所以我决定给一个小型的SSCCE。请告诉我如何实现我所描述的内容，或者如果您觉得这很容易，请修改我的代码。

由于

这是SSCCE：

public class MultiLineList extends JFrame
{

    private static final long serialVersionUID = 1L;

    public static void main(final String[] args)
    {
        new MultiLineList();
    }

    private MultiLineList()
    {
        setTitle("MultiLineList");
        setSize(800, 450);
        setResizable(true);
        setVisible(true);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        this.getContentPane().setLayout(new BorderLayout());

        final DefaultListModel model = new DefaultListModel();
        model.addElement("This is a short text");
        model.addElement("This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. ");
        model.addElement("This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. ");

        final JList list = new JList(model);
        list.setCellRenderer(new MyCellRenderer());

        this.add(list);

        this.getContentPane().invalidate();
        this.getContentPane().validate();

    }

    public class MyCellRenderer extends DefaultListCellRenderer
    {
        @Override
        public Component getListCellRendererComponent(final JList list, final Object value, final int index, final boolean isSelected, final boolean hasFocus)
        {

            final String text = (String) value;

            //create panel
            final JPanel p = new JPanel();
            p.setLayout(new BorderLayout());

            //icon
            final JPanel IconPanel = new JPanel(new BorderLayout());
            final JLabel l = new JLabel("icon"); //<-- this will be an icon instead of a text
            IconPanel.add(l, BorderLayout.NORTH);
            p.add(IconPanel, BorderLayout.WEST);

            //text
            final JTextArea ta = new JTextArea();
            ta.setText(text);
            ta.setLineWrap(true);
            ta.setWrapStyleWord(true);
            p.add(ta, BorderLayout.CENTER);

            return p;

        }
    }

}

Answer 1

编辑1 ：oops - 看到@Andrew的屏幕截图，意识到这没有按预期工作，文本实际上比显示的更长（忽略内部评论“PENDING：不工作JScrollPane中的JList“;-)如果我不能尽快使用它，请稍微挖一下并删除这个答案。

编辑2 ：得到它 - 如下所示的渲染器实现是可以的，罪魁祸首是JList，其偶尔不是最佳大小的缓存。

有两个部分

BasicListUI没有考虑到调整列表大小可能需要清除内部大小（实际行高）缓存，应用程序代码必须强制它这样做，f.i。在ComponentListener
list的trackViewportWidth的Scrollable实现包含阻碍该区域的逻辑（导致该区域的循环伸展直到它是单行），子类返回true。

使用以下渲染器的代码：

    final JList list = new JList(model) {

        /** 
         * @inherited <p>
         */
        @Override
        public boolean getScrollableTracksViewportWidth() {
            return true;
        }


    };
    list.setCellRenderer(new MyCellRenderer());

    ComponentListener l = new ComponentAdapter() {

        @Override
        public void componentResized(ComponentEvent e) {
            // next line possible if list is of type JXList
            // list.invalidateCellSizeCache();
            // for core: force cache invalidation by temporarily setting fixed height
            list.setFixedCellHeight(10);
            list.setFixedCellHeight(-1);
        }

    };

    list.addComponentListener(l);
    add(new JScrollPane(list));

第一个答案（使用JTextArea作为渲染组件的渲染器实现）

TextArea在调整大小时有点棘手：它需要初始化为合理的东西：

public class MyCellRenderer implements ListCellRenderer {

    private JPanel p;
    private JPanel iconPanel;
    private JLabel l;
    private JTextArea ta;

    public MyCellRenderer() {
        p = new JPanel();
        p.setLayout(new BorderLayout());

        // icon
        iconPanel = new JPanel(new BorderLayout());
        l = new JLabel("icon"); // <-- this will be an icon instead of a
                                // text
        iconPanel.add(l, BorderLayout.NORTH);
        p.add(iconPanel, BorderLayout.WEST);

        // text
        ta = new JTextArea();
        ta.setLineWrap(true);
        ta.setWrapStyleWord(true);
        p.add(ta, BorderLayout.CENTER);
    }

    @Override
    public Component getListCellRendererComponent(final JList list,
            final Object value, final int index, final boolean isSelected,
            final boolean hasFocus) {

        ta.setText((String) value);
        int width = list.getWidth();
        // this is just to lure the ta's internal sizing mechanism into action
        if (width > 0)
            ta.setSize(width, Short.MAX_VALUE);
        return p;

    }
}

Answer 2

Multi-Line List

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

public class MultiLineList
{
    private static final long serialVersionUID = 1L;

    public static void main(final String[] args)
    {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new MultiLineList();
            }
        });
    }

    private MultiLineList()
    {
        JFrame f = new JFrame("MultiLineList");
        f.setResizable(true);
        f.setVisible(true);
        f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        f.getContentPane().setLayout(new BorderLayout());

        final DefaultListModel model = new DefaultListModel();
        model.addElement("This is a short text");
        model.addElement("This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. This is a long text. ");
        model.addElement("This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. This is an even longer text. ");

        final JList list = new JList(model);
        list.setCellRenderer(new MyCellRenderer());

        f.add(list);

        f.pack();
    }

    public class MyCellRenderer extends DefaultListCellRenderer
    {
        final JPanel p = new JPanel(new BorderLayout());
        final JPanel IconPanel = new JPanel(new BorderLayout());
        final JLabel l = new JLabel("icon"); //<-- this will be an icon instead of a text
        final JLabel lt = new JLabel();
        String pre = "<html><body style='width: 200px;'>";

        MyCellRenderer() {
            //icon
            IconPanel.add(l, BorderLayout.NORTH);
            p.add(IconPanel, BorderLayout.WEST);

            p.add(lt, BorderLayout.CENTER);
            //text
        }

        @Override
        public Component getListCellRendererComponent(final JList list, final Object value, final int index, final boolean isSelected, final boolean hasFocus)
        {
            final String text = (String) value;
            lt.setText(pre + text);

            return p;
        }
    }
}

Swing JList具有多行文本和动态高度

2 个答案: