jnumberfield.java~1~

java编写的聊天室客户端程序

package chatClient;
import javax.swing.*;
import javax.swing.text.*;
import java.awt.*;

/**
 * 只允许输入数字的JTextField
 *               JNumberField txtNumber1=new JNumberField()
 *                        txtNumber2=new JNumberField(4)
 *                        txtNumber3=new JNumberField(4,12)
 */
public class JNumberField extends JTextField
{
    public JNumberField()
    {
        super();
        setDocument(new numDoc());
    }
    public JNumberField(int decLen)
    {
        super();
        setDocument(new numDoc(decLen));
    }
    public JNumberField(int decLen,int maxLen)
    {
        super();
        setDocument(new numDoc(decLen,maxLen));
    }
}
class numDoc extends PlainDocument
{
        int maxLength=16;
        int decLength=0;
        public numDoc(int decLen,int maxLen)
        {
                maxLength=maxLen;
                decLength=decLen;
        }
        public numDoc(int decLen)
        {
                decLength=decLen;
        }
        public numDoc(){}
        public void insertString(int offset,String s,AttributeSet a)throws BadLocationException
        {
                int len=getLength();
                String str=getText(0,len);
                int decPos=str.indexOf(".");
                if (
                s.equals("F")||s.equals("f")||s.equals("D")||s.equals("d")
                ||(str+s).length()>maxLength
                ||(decPos>-1&&offset>decPos&&((str.substring(decPos+1))+s).length()>decLength)
                ||(str.trim().equals("0")&&!s.substring(0,1).equals(".")&&offset!=0)
                ||(s.equals(".")&&decLength==0)
                ||(s.indexOf(".")>-1&&s.substring(s.indexOf(".")+1).length()>decLength)
                )
                {
                    Toolkit.getDefaultToolkit().beep();
                    return;
                }
                try{
                    Float.parseFloat(str+s);
                }catch(Exception e){
                    Toolkit.getDefaultToolkit().beep();
                    return;
                }
                super.insertString(offset,s,a);
        }
}