String Program using java 8

import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.stream.Collectors;

//Count occurrence of each character
// find dublicate Character in string
//Count words in string -> "java is good" -> 3 word 
//Count the word Occurance -> " java is good but java is hard"   -> {but=1, =1, java=2, is=2, hard=1, good=1}
//count the character in words -> "java is good"=> 4-> [java,good], 2->[is]




//----------------need to more practice-------------------------
//Count vowels
//Find longest word -> max(Comparator.comparing(String::length)).get()
//First non-repeating character

class Codechef
{
    public static void main(String[] args) throws java.lang.Exception
    {
        String str = "Programming";

        //     Map < Character, Long > map = str.chars()
        //         .mapToObj(c -> (char) c)
        //         .map(Character::toLowerCase) // ⭐ important line
        //         .collect(Collectors.groupingBy(c -> c, Collectors.counting()));

        //     System.out.println(map);

        //  ⭐    // find dublicate Character in string
        //     Set<Character>set = new HashSet<>();
        //     str.chars().mapToObj(c-> (char) c).filter(c-> !set.add(c)).forEach(c-> System.out.print(c+" "));


        //     System.out.println("");
        //  ⭐    //Count vowels
        //     str.chars().mapToObj(c-> (char)c).filter(c-> "aeiou".contains(String.valueOf(c))).forEach(n-> System.out.print(n+ " "));


        //⭐ reverse string -----------------------
        //StringBuilder sb = new StringBuilder(str);
        //String reverse= sb.reverse().toString();
        // System.out.println(reverse);

        //⭐ Palindrome string-------------------------& reverse string
        //  StringBuilder sb2 = new StringBuilder(str);
        //  Boolean palindrome = str.equals(sb2.reverse().toString());
        //  System.out.println(palindrome);


        ////⭐ count the word Occurance or frequesncy--------------------
        String str2 = " java is good but java language is hard";
        Map < String, Long > map4 = Arrays.stream(str2.split(" ")).collect(Collectors.groupingBy(s -> s, Collectors.counting()));
        System.out.println(map4);

        //⭐ Count words in string -> "java is good" -> 3 word 
        //   Long count =  str.chars().mapToObj(c-> (char)c).filter(c-> "aeiou".contains(String.valueOf(c))).count();
        //     System.out.println("Count: "+count);
        
        //⭐ count the character in words -> "java is good"=> 4-> [java,good], 2->[is]
        
        String str3 = "java is good language is";
        

        //Find longest word ⭐ important 
        String longest = Arrays.stream(str2.split(" ")).max(Comparator.comparing(String::length)).get();
        long longestCount = longest.length();
        System.out.println("Longest: " + longest + " Count: " + longestCount);

    }
}