gistfile1.txt

/*
 * SK's Minecraft Launcher
 * Copyright (C) 2010-2014 Albert Pham <http://www.sk89q.com> and contributors
 * Please see LICENSE.txt for license information.
 */

package com.skcraft.launcher.util;

import javax.swing.*;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.Element;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AbstractDocument.BranchElement;

/**
 * From http://tips4java.wordpress.com/2008/10/15/limit-lines-in-document/
 * 
 * @author Rob Camick
 */
public class LimitLinesDocumentListener implements DocumentListener {
    private int maximumLines;
    private boolean isRemoveFromStart;
    private volatile int removing;

    /**
     * Specify the number of lines to be stored in the Document. Extra lines
     * will be removed from the start or end of the Document, depending on
     * the boolean value specified.
     * 
     * @param maximumLines number of lines
     * @param isRemoveFromStart true to remove from the start
     */
    public LimitLinesDocumentListener(int maximumLines,
                                      boolean isRemoveFromStart) {
        setLimitLines(maximumLines);
        this.isRemoveFromStart = isRemoveFromStart;
	this.removing = 0;
    }

    /**
     * Set the maximum number of lines to be stored in the Document
     * 
     * @param maximumLines number of lines
     */
    public void setLimitLines(int maximumLines) {
        if (maximumLines < 1) {
            throw new IllegalArgumentException("Maximum lines must be greater than 0");
        }

        this.maximumLines = maximumLines;
    }

    @Override
    public void insertUpdate(final DocumentEvent e) {
        // Changes to the Document can not be done within the listener
        // so we need to add the processing to the end of the EDT

        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
		if (!this.removing) {
                	removeLines(e);
			this.removing = 1;
		}
            }
        });
    }

    @Override
    public void removeUpdate(DocumentEvent e) {
    }

    @Override
    public void changedUpdate(DocumentEvent e) {
    }

    private void removeLines(DocumentEvent e) {
	System.out.println(">removeLines");
        // The root Element of the Document will tell us the total number
        // of line in the Document.

        Document document = e.getDocument();
        BranchElement root = (BranchElement) document.getDefaultRootElement();
	int elements = root.getElementCount();
	int new_elements;
	int excess = elements - maximumLines;
	if (excess > 0) {
            if (isRemoveFromStart) {
	        root.replace(0, excess, new Element[0]);
            } else {
                root.replace(elements - excess, excess, new Element[0]);
            }
        }
	new_elements = root.getElementCount();
	if (new_elements > maximumLines) {
	    System.out.printf("After removing lines (%d), still have %d/%d lines.\n", elements, new_elements, maximumLines);
	}
	this.removing = 0;
	System.out.println("<removeLines");
    }
}