how to shuffle string java

To shuffle a string in Java, you can use the shuffle method of the Collections class and pass it a List containing the characters of the string.

Here's an example of how you can do this:

import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args) {
        String s = "abcdefghijklmnopqrstuvwxyz";
        List<Character> characters = s.chars().mapToObj(c -> (char) c).collect(Collectors.toList());
        Collections.shuffle(characters);
        String shuffled = characters.stream().map(Object::toString).collect(Collectors.joining());
        System.out.println(shuffled);
    }
}

This code will shuffle the characters of the string using the shuffle method of the Collections class, and then create a new string by joining the shuffled characters together using the stream and collect methods.

You can also use the shuffle method of the Collections class to shuffle the characters of a StringBuilder or StringBuffer object, if you need to shuffle a string in-place:

import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args) {
        StringBuilder sb = new StringBuilder("abcdefghijklmnopqrstuvwxyz");
        List<Character> characters = sb.chars().mapToObj(c -> (char) c).collect(Collectors.toList());
        Collections.shuffle(characters);
        sb.setLength(0);
        characters.forEach(sb::append);
        System.out.println(sb);
    }
}

This code will shuffle the characters of the StringBuilder object in-place and print the shuffled string to the console.