Need help with while loops

[tangel]

I am supposed to write a program that asks the user to enter an English sentence, phrase or paragraph, and then test the input for various properties.

The program has to allow the user to enter a sentence (through a dialog), and will respond by telling the user the answer to the following questions:

Is the input a palindrome?


here is what i have so far:

import java.util.*;

public class Lab4
{
public static void main(String[]args)
{
Scanner in = new Scanner(System.in);

//variables

String input ;
String line;
int length, pos1, pos2;
char char1, char2;

// Prompt, get, and save sentence
System.out.println("Please enter a sentence:");
input = in.nextLine();
System.out.println("Your input was: " + input + ".");

// Is the input a palindrome?
pos1 = 0;
pos2 =input.length()-1;

while (pos2>0)
{
char1=input.charAt(pos1);
char2=input.charAt(pos2);

if(char1 == char2)
{
pos1++;
pos2--;
}

else if (char1 == ',' || char1 == '.' ||
char1 == '-' || char1 == ':' ||
char1 == ';' || char1 == ' ')
pos1++;
else if (char2 == ',' || char2 == '.' ||
char2 == '-' || char2 == ':' ||
char2 == ';' || char2 == ' ')
pos2--;
else
break;
}
System.out.println();


if (pos1< pos2)
System.out.println ("That string is NOT a palindrome.");
else

System.out.println ("That string IS a palindrome.");
}
}

i dont understand what i'm doing wrong. i am comparing the last and first character and moving toward the center. i also attempted to make sure it skipped punctuation and spaces. can somebody please help me?