When should we use intern method of String on String literals

Question

According to String#intern(), intern method is supposed to return the String from the String pool if the String is found in String pool, otherwise a new string

Answer 1

As you said, that string intern() method will first find from the String pool, if it finds, then it will return the object that points to that, or will add a new String into the pool.

    String s1 = "Hello";
    String s2 = "Hello";
    String s3 = "Hello".intern();
    String s4 = new String("Hello");

    System.out.println(s1 == s2);//true
    System.out.println(s1 == s3);//true
    System.out.println(s1 == s4.intern());//true

The s1 and s2 are two objects pointing to the String pool "Hello", and using "Hello".intern() will find that s1 and s2. So "s1 == s3" returns true, as well as to the s3.intern().