If == compares references in Java, why does it evaluate to true with these Strings?

As it is stated the == operator compares object references to check if they are referring to the same object on a heap. If so why am I getting the "Equal" for this piece of code?

public class Salmon {
    public static void main(String[] args) {

        String str1 = "Str1";
        String str2 = "Str1";

        if (str1 == str2) {
            System.out.println("Equal");
        } else {
            System.out.println("Not equal");
        }
    }
}