Create a multiline JLabel in Java

Description

The following code shows how to create a multiline JLabel.

Example


/*from ww w.  j av  a 2  s.c  om*/
import java.awt.Color;
import java.awt.Component;
import java.awt.Font;
import java.util.ArrayList;
import java.util.List;

import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JFrame;

public class Main {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Popup JComboBox");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    frame.add(new MultiLineLabel("java2s.com\njava2s.com"));
    frame.setSize(300, 200);
    frame.setVisible(true);
  }

}
/**
 ** @version $Id: MultiLineLabel.java 6164 2009-02-19 18:11:32Z polle $
 ** @author Justin Tan
 ** A multi-line Label-like AWT component.
 **/
 class MultiLineLabel extends JPanel
{
    protected int fontAttributes = Font.PLAIN;
    protected float alignment;
    protected Color col = null;
  protected int spacing = 0;
    
    /**
     ** Constructor - make a multiline label
     **/
    public MultiLineLabel(String text, float alignment)
    {
        this.alignment = alignment;
        setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
        if(text != null)
            setText(text);
    }

    /**
     ** Constructor, defaults to centered text
     **/
    public MultiLineLabel(String text)
    {
        this(text, LEFT_ALIGNMENT);
    }

    /**
     * Constructor, empty with the given alignment
     */
    public MultiLineLabel(float alignment)
    {
        this(null, alignment);
    }

    /**
     * Constructor, empty with the given alignment and line spacing
     */
    public MultiLineLabel(float alignment, int spacing)
    {
        this(null, alignment);
        this.spacing = spacing;
    }

    /**
     ** Constructor - make an empty multiline label
     **/
    public MultiLineLabel()
    {
        this(null, LEFT_ALIGNMENT);
    }
  
    public void setText(String text)
    {
        // clear the existing lines from the panel
        removeAll();
        addText(text);
    }
  
    public void addText(String text)
    {
        addText(text, 12);
    }
    
    public void addText(String text, int size)
    {
        if(spacing > 0)
            add(Box.createVerticalStrut(spacing));

        String strs[] = splitLines(text);
        JLabel l;
        Font font = new Font("SansSerif", fontAttributes, size);

        for (int i = 0; strs != null && i < strs.length; i++) {
            l = new JLabel(strs[i]);
            l.setFont(font);
            l.setAlignmentX(alignment);

            if (col != null)
                l.setForeground(col);

            add(l);
        }   
    }

    /**
     * Splits "string" by "Delimiter"
     * 
     * @param str - the string to be split
     * @param delimiter - the field delimiter within str
     * @returns an array of Strings
     */
    public static String[] split(String str, String delimiter)
    {
        List<String> strings = new ArrayList<String>();
        int start = 0;
        int len = str.length();
        int dlen = delimiter.length();
        int offset = str.lastIndexOf(delimiter); // First of all, find the
        // Last occurance of the Delimiter
        // Stop empty delimiters
        if (dlen < 1)
            return null;
        else if (offset < 0) // one element
        {
            String[] result = {str};
            return result;
        }

        //
        // Append the delimiter onto the end if it doesn't already exit
        //
        if (len > offset + dlen) {
            str += delimiter;
            len += dlen;
        }

        do {
            // Get the new Offset
            offset = str.indexOf(delimiter, start);
            strings.add(str.substring(start, offset));

            // Get the new Start position
            start = offset + dlen;
        } while ((start < len) && (offset != -1));

        // Convert the list into an Array of Strings
        String result[] = new String[strings.size()];
        strings.toArray(result);
        return result;
    }

    /**
     * Splits "string" into lines (stripping end-of-line characters)
     * 
     * @param str - the string to be split
     * @returns an array of Strings
     */
    public static String[] splitLines(String str)
    {
        return (str == null ? null : split(str, "\n"));
    }

    public void addText(String text, boolean bold, boolean italic)
    {
        int oldAttributes = fontAttributes;
        setBold(bold);
        setItalic(italic);
        addText(text);
        fontAttributes = oldAttributes;
    }

    public void setForeground(Color col)
    {
        this.col = col;    
        Component[] components = this.getComponents();
        for (int i = 0; i < components.length; i++) {
      Component component = components[i];
      component.setForeground(col);
    }
    }
      
    public void setItalic(boolean italic)
    {
        if(italic)
           fontAttributes |= Font.ITALIC;
        else
            fontAttributes &= ~Font.ITALIC;
    }
  
    public void setBold(boolean bold)
    {
        if(bold)
            fontAttributes |= Font.BOLD;
        else
            fontAttributes &= ~Font.BOLD;
    }
}
/*
 This file is part of the BlueJ program. 
 Copyright (C) 1999-2009  Michael K?lling and John Rosenberg 
 
 This program is free software; you can redistribute it and/or 
 modify it under the terms of the GNU General Public License 
 as published by the Free Software Foundation; either version 2 
 of the License, or (at your option) any later version. 
 
 This program is distributed in the hope that it will be useful, 
 but WITHOUT ANY WARRANTY; without even the implied warranty of 
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 GNU General Public License for more details. 
 
 You should have received a copy of the GNU General Public License 
 along with this program; if not, write to the Free Software 
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA. 
 
 This file is subject to the Classpath exception as provided in the  
 LICENSE.txt file that accompanied this code.
 */

The code above generates the following result.

Create a multiline JLabel in Java




















Home »
  Java Tutorial »
    Swing »




Action
Border
Color Chooser
Drag and Drop
Event
Font Chooser
JButton
JCheckBox
JComboBox
JDialog
JEditorPane
JFileChooser
JFormattedText
JFrame
JLabel
JList
JOptionPane
JPasswordField
JProgressBar
JRadioButton
JScrollBar
JScrollPane
JSeparator
JSlider
JSpinner
JSplitPane
JTabbedPane
JTable
JTextArea
JTextField
JTextPane
JToggleButton
JToolTip
JTree
Layout
Menu
Timer