package com;

import java.awt.Toolkit;

import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;

public class LimitedDocument extends PlainDocument {  
	  
    private static final long serialVersionUID = 1L;  
    private int maxLength = -1;
    private String allowCharAsString = null;
  
    public LimitedDocument() {  
        super();  
    }  
  
    public LimitedDocument(int maxLength, String allow_chars) {  
        super();  
        this.maxLength = maxLength;
        allowCharAsString = allow_chars;
    }  
  
    public void insertString(int offset, String str, AttributeSet attrSet) throws BadLocationException {  
        if (str == null) {  
            return;  
        }  
        if (allowCharAsString != null && str.length() == 1) {  
            if (allowCharAsString.indexOf(str) == -1) {  
                return;
            }  
        }  
        char[] charVal = str.toCharArray();  
        String strOldValue = getText(0, getLength());  
        char[] tmp = strOldValue.toCharArray();  
        if (maxLength != -1 && (tmp.length + charVal.length > maxLength)) {  
            Toolkit.getDefaultToolkit().beep();
            return;
        }  
        super.insertString(offset, str, attrSet);  
    }  
  
    public void setAllowChar(String str) {  
        allowCharAsString = str;  
    }  
}