Generate palindrome words

Question

So, I have this code which generates palindrome words in a special manner. 1> it joins the word by its reverse(excluding last character). 2> the words which end with repeated alphabets, for example ABB becomes ABBA and not ABBBA and XAZZZ becomes XAZZZAX. I am already done with the first part. I have just tried second one by extracting last two characters, because to be honest, I don't know how should I do it.

import java.io.*;
class ISC_Q3_2019
{
    public static void main(String args[])throws IOException
    {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        ISC_Q3_2019 ob = new ISC_Q3_2019();
        System.out.println("Enter your sentence");
        String s = br.readLine();
        s=s.toUpperCase();
        String words[] = s.split(" ");
        int l=words.length;
        char ch1=s.charAt(s.length()-1);
        String ans=" ", copy=" ", p=" ";
        if(ch1=='.'||ch1=='!'||ch1=='?')
        {
            for(int i=0;i<l;i++)
            {
                if(ob.isPalindrome(words[i])==true)
                {
                    ans=ans+words[i];
                }
                else
                {
                    copy=words[i];
                    words[i]=ob.Reverse(words[i]);
                    p=copy.concat(words[i]);
                    ans=ans+p;
                }
            }
            System.out.println("OUTPUT:" +ans.trim());
        }
        else
            System.out.println("Invalid Input!");
    }
    boolean isPalindrome(String s)
    {
        s=s.toUpperCase();
        int l=s.length();
        char ch;
        String rev=" ", copy=" ";
        copy=s;
        for(int i=l-1;i>=0;i--)
        {
            ch=s.charAt(i);
            rev=rev+ch;
        }
        if(rev.equals(copy))
            return true;
        else
            return false;
    }
    String Reverse(String s)
    {
        s=s.toUpperCase();
        int l=s.length();
        char ch, ch1, ch2;
        String r=" ";
        for(int i=l-2;i>=0;i--)
        {
            ch=s.charAt(i);
            ch1=s.charAt(l-1);
            ch2=s.charAt(l-2);
            if(ch1==ch2)
                r=r+ch;
            else
                r=r+ch;
            }
        return r;
    }
}

OUTPUT:

Enter your sentence The abb is flying.

**OUTPUT:**THE HTABB BAIS IFLYING. GNIYLF

And another part I am concerned is the unmatched spaces.

Answer 1

Here you go

import java.util.Arrays;
import java.util.List;
import java.util.Scanner;
import java.util.stream.Collectors;

public class Palindrome {
    public static void main(String... args) {
        // Request for input
        Scanner reader = new Scanner(System.in);
        System.out.println("Enter your sentence...");

        // Read the user input
        String sentence = reader.nextLine();

        // Split the sentence (into tokens) at spaces and special characters using regex
        // Keep the special characters where they are and form a List with the split words
        List<String> tokens = Arrays.asList(sentence.split("((?<=[\\?,\\. ])|(?=[\\?,\\. ]))"));

        // For every token/word, form the palindrome of that and then join them back
        String result = tokens.stream().map(s -> formPalindrome(s)).collect(Collectors.joining());

        // This is the final result
        System.out.println("result: " + result);

        reader.close();
    }

    private static String formPalindrome(String str) {
        // Reverse the String
        String reversed = new StringBuilder(str).reverse().toString();

        // String length
        int strLen = reversed.length();

        // Compare each character of reversed string with last character of the string until they are different
        // When they are different concat the substring with original string
        for (int i = 0; i < strLen; i++) {
            if (reversed.charAt(i) != str.charAt(strLen - 1)) {
                return str + reversed.substring(i);
            }
        }

        return str;
    }
}