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javastringstring-literals

String hashCodes

Small question.

String s1 = "test";
String s2 = "test";

s1,s2 both have same hashCode value

String sn1 = new String("java");
String sn2 = new String("java");

all of them said sn1 and sn2 have different hashCode values and those are different objects

When I am printing hashCode values it gives same value that means sn1 and sn2 points to the same object or not ?

Solution

  • It is often useful to look at the java code to see what is happening.

    For example the String#hashCode method

    public int hashCode() {
    int h = hash;
    if (h == 0) {
        int off = offset;
        char val[] = value;
        int len = count;

            for (int i = 0; i < len; i++) {
                h = 31*h + val[off++];
            }
            hash = h;
        }
        return h;
    }

    As you can see the result is based upon the value of the String, not its memory location.