fixedlengthdocument.java

java编写的聊天室客户端程序

package chatClient;

import javax.swing.*;
import javax.swing.text.*;
import java.awt.Toolkit;


public class FixedLengthDocument extends PlainDocument {
    private int maxLength;

        public FixedLengthDocument(int maxLength){
                this.maxLength = maxLength;
        }

        public void insertString(int offset,String str,AttributeSet att) throws BadLocationException
        {
                if ( getLength() + str.length() > maxLength ){
                        Toolkit.getDefaultToolkit().beep();
                }else{
                        super.insertString(offset,str,att);
                }
        }

}