Java tutorial
/* * Copyright (c) 1995, 2008, Oracle and/or its affiliates. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * - Neither the name of Oracle or the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ package components; /* A 1.4 class used by TextComponentDemo.java. */ import javax.swing.*; import javax.swing.text.*; import java.awt.Toolkit; public class DocumentSizeFilter extends DocumentFilter { int maxCharacters; boolean DEBUG = false; public DocumentSizeFilter(int maxChars) { maxCharacters = maxChars; } public void insertString(FilterBypass fb, int offs, String str, AttributeSet a) throws BadLocationException { if (DEBUG) { System.out.println("in DocumentSizeFilter's insertString method"); } //This rejects the entire insertion if it would make //the contents too long. Another option would be //to truncate the inserted string so the contents //would be exactly maxCharacters in length. if ((fb.getDocument().getLength() + str.length()) <= maxCharacters) super.insertString(fb, offs, str, a); else Toolkit.getDefaultToolkit().beep(); } public void replace(FilterBypass fb, int offs, int length, String str, AttributeSet a) throws BadLocationException { if (DEBUG) { System.out.println("in DocumentSizeFilter's replace method"); } //This rejects the entire replacement if it would make //the contents too long. Another option would be //to truncate the replacement string so the contents //would be exactly maxCharacters in length. if ((fb.getDocument().getLength() + str.length() - length) <= maxCharacters) super.replace(fb, offs, length, str, a); else Toolkit.getDefaultToolkit().beep(); } }