根据内容展开JList行高

Question

I have a simple problem which totally drives me crazy.

I have a JList, and would like its cells to expand depending on their content, which is text of variable length.

So I created a CustomCellRenderer like so:

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

    final JTextArea ta = new JTextArea();
    ta.setText(text);
    ta.setFont(new Font("Dialog", Font.PLAIN, (int) Theme.FONTSIZE_TEXT));
    ta.setForeground(Theme.FONTCOLOR_CONTENT);
    ta.setLineWrap(true);
    ta.setWrapStyleWord(true);
    ta.setColumns(0);
    ta.setBorder(BorderFactory.createEmptyBorder(10, Theme.PADDING, 0, 0));
    return ta;
}

but the cells are only one text line high and the rest of the JTextArea is cut off. If I add

ta.setPreferredSize(new Dimension(0, 70));

I get a row height of 70 and I can see more of the JTextArea's text, but still not everything.

Is there any way to make JList expand its cells so that the whole content of the JTextArea is displayed?

Answer 1

there are maybe easiest and nicest way, I think that JTable with one TableColumn (and without TableHeader)in all cases better as JList , here is your Render MacOX version

then output should be

import java.awt.*;
import javax.swing.*;
import javax.swing.table.*;
import javax.swing.text.*;
//http://tips4java.wordpress.com/2008/10/26/text-utilities/
public class AutoWrapTest {

    public JComponent makeUI() {
        String[] columnNames = {" Text Area Cell Renderer "};
        Object[][] data = {
            {"123456789012345678901234567890"},
            {"dddddddddddddddddddddddddddddddddddddddddddddddddddddddddx"},
            {"----------------------------------------------0"},
            {">>>>>>>>>>>>>dddddddddddddddddddddddddddddddddddddddddddddddddd"
                + "dddddddxdddddddddddddddddddddddddddddddddddddddddddddd"
                + "dddddddddddx>>>>>>>>>>>>>>>>>>>>>>>>>|"},
            {">>>>>>>>>>>>ddddddddddddddddddddddddddddddddddddddddddddddddddd"
                + "ddddddx>>>>>>>>>>>>>>>>>>>>>>>>>>|"},
            {"a|"},
            {">>>>>>>>bbbb>>>>>>>>>>>>>>>>>>>|"},
            {">>>>>>>>>>>>>>>>>>|"},
            {">>>>>>>>>>>>>dddddddddddddddddddddddddddddddddddddddddddddddddd"
                + "dddddddxdddddddddddddd123456789012345678901234567890dddddd"
                + "dddddddddddddddddddddddddddddddddddddx>>>>>>>>>>>>>>>>>>>>"
                + ">>>>>|"},
            {">>>>>>>>>>>>>dddddddddddddd123456789012345678901234567890dddddd"
                + "dddddddddddddddddddddddddddddddddddddxdddddddddddddd123456"
                + "789012345678901234567890dddddddddddddddddddddddddddddddddd"
                + "ddddd123456789012345678901234567890ddddx>>>>>>>>>>>>>>>>>>"
                + ">>>>>>>|"},};
        TableModel model = new DefaultTableModel(data, columnNames) {

            private static final long serialVersionUID = 1L;

            @Override
            public boolean isCellEditable(int row, int column) {
                return false;
            }
        };
        JTable table = new JTable(model) {

            private static final long serialVersionUID = 1L;

            @Override
            public void doLayout() {
                TableColumn col = getColumnModel().getColumn(0);
                for (int row = 0; row < getRowCount(); row++) {
                    Component c = prepareRenderer(col.getCellRenderer(), row, 0);
                    if (c instanceof JTextArea) {
                        JTextArea a = (JTextArea) c;
                        int h = getPreferredHeight(a) + getIntercellSpacing().height;
                        if (getRowHeight(row) != h) {
                            setRowHeight(row, h);
                        }
                    }
                }
                super.doLayout();
            }

            private int getPreferredHeight(JTextComponent c) {
                Insets insets = c.getInsets();
                View view = c.getUI().getRootView(c).getView(0);
                int preferredHeight = (int) view.getPreferredSpan(View.Y_AXIS);
                return preferredHeight + insets.top + insets.bottom;
            }
        };
        table.setEnabled(false);
        table.setShowGrid(false);
        table.setTableHeader(null);
        table.getColumnModel().getColumn(0).setCellRenderer(new TextAreaCellRenderer());
        //table.setPreferredScrollableViewportSize(table.getPreferredSize());
        JScrollPane sp = new JScrollPane(table);
        sp.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
        sp.setPreferredSize(new Dimension(250, 533));
        JPanel p = new JPanel(new BorderLayout());
        p.add(sp);
        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 AutoWrapTest().makeUI());
        f.setLocation(100, 100);
        f.pack();
        f.setVisible(true);
    }
}

class TextAreaCellRenderer extends JTextArea implements TableCellRenderer {

    private static final long serialVersionUID = 1L;
    private final Color evenColor = new Color(230, 240, 255);

    public TextAreaCellRenderer() {
        super();
        setLineWrap(true);
        setBorder(BorderFactory.createEmptyBorder(2, 2, 2, 2));
    }

    @Override
    public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {
        if (isSelected) {
            setForeground(table.getSelectionForeground());
            setBackground(table.getSelectionBackground());
        } else {
            setForeground(table.getForeground());
            setBackground(table.getBackground());
            setBackground((row % 2 == 0) ? evenColor : getBackground());
        }
        setFont(table.getFont());
        setText((value == null) ? "" : value.toString());
        return this;
    }
}

Answer 2

Not sure if there is an elegant way. One way that I know works is as follows : In getListCellRendererComponent()

• Use JLabel for the renderer
• Convert the text in question to HTML and use some logic to insert <br> in to the text where desired.
• Then set the text as text for the JLabel component and return.

Answer 3

尝试使用JList的setFixedCellHeight（）方法。