验证回文串（java）

import java.util.*;
import javax.swing.*;
/******************************************************
This is a progrem judge whether a word is palindrome
*******************************************************/
public class text1
{
public static void main(String[] args)
{
String judge="yes";//use for while
while(judge.equals("yes"))
{
String aword=JOptionPane.showInputDialog("Input a word:");
ReturnWord r=new ReturnWord(aword.toLowerCase());//build ReturnWord than init it

if(r.testReturnWord())//if aword is a palindrome show message
JOptionPane.showMessageDialog(null,aword+" is a palindrome.");
if(!r.testReturnWord())
JOptionPane.showMessageDialog(null,"Error! "+aword+" is not a palindrome!");
//suggestive words
judge=JOptionPane.showInputDialog("Do you want again?(Input yes or no ):");
if(!judge.equals("yes")&&!judge.equals("no"))
JOptionPane.showMessageDialog(null,judge+" is Error! "+"system will quit!");
}
System.exit(0);//exit
}
}
// palindrome class
class ReturnWord
{
public ReturnWord(String word)
{
this.word=word;
}
//test word wether a palindrome
public boolean testReturnWord()
{

int i=0,j=word.length()-1,k=1;
while(i<=j)
{
if(word.charAt(i)>='a'&&word.charAt(i)<='z')
{
while(j>=0)
{
if(word.charAt(j)>='a'&&word.charAt(j)<='z')
{
if(word.charAt(i)==word.charAt(j))
{
j--;
break;
}
else
{
k=0;
break;
}
}
j--;
}
}
if(k==0)break;
i++;
}
if(k==0)return false;
else return true;
}
private String word;
}