Java String variable setting - reference or value?

Question

The following Java code segment is from an AP Computer Science practice exam.

String s1 = \"ab\";
String s2 = s1;
s1 = s1 + \"c\";
System.out.println(s1 + \"         


        

Answer 1

java.lang.String is an object, not a primitive.

What the code did in the first example is:

1. Define s1 as "ab"
2. Set s2 equal to the same underlying object as s1
3. Set s1 equal to a new string that is the combination of s1's old value and "c"

But to answer your question about reference or value, it's by reference.