String immutability

 String is completely thread safe.

https://www.techiedelight.com/why-override-equals-and-hashcode-methods-java/


package org.example;

public class Main {
    public static void main(String[] args) {
        String s = "Hello";
        s.concat(" World");
        System.out.println(s);

        s = s.concat(" World");
        System.out.println(s);
    }
}

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