求JAVA入门小程序源代码

mport java.util.*;
public class HuiWen
{
public static void main(String[] args)
{
Scanner in=new Scanner(System.in);
System.out.println("please input a String:");
String st=in.nextLine();
String s=st.toLowerCase();
int i=0;
int j=s.length()-1;
boolean t=true;
char first=s.charAt(i);
char last=s.charAt(j);
for(;i<j;)
{
while(!(first>='a'&&first<='z'))
{
i++;
first=s.charAt(i);
}
while(!(last>='a'&&last<='z'))
{
j--;
last=s.charAt(i);
}
if(i>=j)
break;
if(first==last)
{
i++;
j--;