java - 使用 JList 和 ListCellRenderer 在 ListCell 上显示多行文本

Question

此类实例由我的 ListCellRenderer 返回:

    public class SessionQALine extends JPanel {
    private JTextArea question;
    private JLabel answer;
    public SessionQALine() {
        setLayout(new BoxLayout(this,BoxLayout.X_AXIS));
        setOpaque(false);
        question = new JTextArea();
        question.setLineWrap(true);
        question.setWrapStyleWord(true);
        question.setFont(new Font(Font.SERIF, Font.ITALIC|Font.BOLD, 14));
        question.setOpaque(false);
        answer = new JLabel();
        answer.setFont(new Font(Font.SERIF, Font.BOLD, 10));
        answer.setOpaque(false);
            add(question);
        add(Box.createHorizontalGlue());
        add(answer);
    }

    public void setQuestion(String q) {
        question.setText(q);
    }
    public void setAnswer(String q) {
        answer.setText(q);
    }
    @Override
    public void paint(Graphics g) {
        super.paint(g);
        g.drawLine(0, getHeight()-1, getWidth(), getHeight()-1);
    }
}

这是我的 ListCellRenderer 的一部分:

private SessionQALine qaLine = new SessionQALine();
@Override
public Component getListCellRendererComponent(JList list, Object value,
        int index, boolean isSelected, boolean cellHasFocus) {
    qaLine.setQuestion(questions.get(index));
    qaLine.setAnswer(answers.get(index));
    return qaLine;
}

当字符串适合一行时，一切正常，但如果需要多于一行，则第二行及以上似乎不会被考虑在内，JList 会绘制单元格，而这些行永远不会显示，是吗？知道我该如何解决这个问题吗？

Answer 1

• 对于 JList 或 JTable 最容易使用 doLayout()，而不是 getPreferredSize java.swing.text.FieldView

• 最方便的是将 JTextArea 放入 JScrollPane，以便更好地输出到 GUI，

• 注意，然后必须将 MouseScrollEvents 从父级 JScrollPane 重定向到鼠标光标下的 JScrollPane，(五六行 code_lines 而且这里解决了几次)

• 使用Borders或JSeparator代替drawLine()

你的意思是

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;
    }
}