Convert to Palindromic Words

Program to accept a sentence which is terminated by ‘.’ or ‘?’ or ‘!’ only. Check for Palindromic Words and convert the non-Palindromic Words to Palindromic Words.

A Palindromic Word is a word which can be spelled same if it is reversed.

Example: “The water level is rising.”. The program is expected to generate new sentence that is “ThehT wateretaw level isi risingnisir”.

Java

import java.util.*;
public class CovPalindromicWord
{
    public static void main(String args[])
    {
        String str="",nstr="",wrd="",rev="";
        char ch=' ';
        int l=0;
        Scanner sc=new Scanner(System.in);
        System.out.println("Enter a sentence ending with '.' or '?' or '!'");
        str=sc.nextLine();
        str=str.trim();
        l=str.length();
        ch=str.charAt(l-1);
        if(!(ch=='.'||ch=='?'||ch=='!'))
        {
            System.out.println("Error! Sentence must be terminated by punctuation");
            System.exit(1);
        }
        for(int i=0;i<l;i++)
        {
            ch=str.charAt(i);
            if(ch==' '||ch=='.'||ch=='?'||ch=='!')
            {
                if(wrd.equalsIgnoreCase(rev))
                {
                    nstr=nstr+wrd+" ";
                }
                else
                {
                    rev=rev.substring(1);
                    nstr=nstr+wrd+rev+" ";
                }
                wrd="";
                rev="";
            }
            else
            {
                wrd=wrd+ch;
                rev=ch+rev;
            }
        }
        System.out.println("New string: "+nstr);
    }
}

Java