Java Swing How to - Create Tab character JList renderer

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Question

We would like to know how to create Tab character JList renderer.

Answer

/* w  w w.j  a  va 2  s .c o  m*/


import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Insets;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.util.StringTokenizer;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.ListCellRenderer;
import javax.swing.UIManager;
import javax.swing.border.Border;
import javax.swing.border.EmptyBorder;

public class Main extends JFrame {

    protected JList list;

    public Main() {
        super("Swing List with Tab Renenderer");
        setSize(500, 240);

        String[] items = { "cloumn 1\t column  2\t Column 3",
                "cloumn 1\t column  2\t Column 3" };

        list = new JList(items);

        TabListCellRenderer renderer = new TabListCellRenderer();
        list.setCellRenderer(renderer);

        JScrollPane scrollPane = new JScrollPane();
        scrollPane.getViewport().add(list);
        getContentPane().add(scrollPane, BorderLayout.CENTER);

        WindowListener exitEvent = new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        };
        addWindowListener(exitEvent);

        setVisible(true);
    }

    public static void main(String argv[]) {
        new Main();
    }
}

class TabListCellRenderer extends JLabel implements ListCellRenderer {
    protected static Border m_noFocusBorder = new EmptyBorder(1, 1, 1, 1);

    protected FontMetrics m_fm = null;

    public TabListCellRenderer() {
        super();
        setOpaque(true);
        setBorder(m_noFocusBorder);
    }

    public Component getListCellRendererComponent(JList list, Object value,
            int index, boolean isSelected, boolean cellHasFocus) {
        setText(value.toString());

        setBackground(isSelected ? list.getSelectionBackground() : list
                .getBackground());
        setForeground(isSelected ? list.getSelectionForeground() : list
                .getForeground());

        setFont(list.getFont());
        setBorder((cellHasFocus) ? UIManager
                .getBorder("List.focusCellHighlightBorder") : m_noFocusBorder);

        return this;
    }

    public void paint(Graphics g) {
        m_fm = g.getFontMetrics();

        g.setColor(getBackground());
        g.fillRect(0, 0, getWidth(), getHeight());
        getBorder().paintBorder(this, g, 0, 0, getWidth(), getHeight());

        g.setColor(getForeground());
        g.setFont(getFont());
        Insets insets = getInsets();
        int x = insets.left;
        int y = insets.top + m_fm.getAscent();

        StringTokenizer st = new StringTokenizer(getText(), "\t");
        while (st.hasMoreTokens()) {
            String str = st.nextToken();
            g.drawString(str, x, y);
            //insert distance for each tab
            x += m_fm.stringWidth(str) + 50;

            if (!st.hasMoreTokens())
                break;
        }
    }
}

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