// 3 public class Variables { public static void main(String[] args) { A a = new A(); a.val = 1; inc(a); System.out.println(a.val); set(a); System.out.println(a.val); } public static class A { public int val; } public static void inc(A a) { a.val++; } public static void set(A a) { a = new A(); a.val = 10; } }

This code does the following:

1. Creates an object A a = new A(); with a field val.
2. Sets a.val to 1.
3. Calls the method inc(a), which increases a.val by 1. Now a.val equals 2.
4. Prints a.val — the output will be 2.
5. Calls the method set(a), in which the parameter a is locally reassigned to a new object new A() with val = 10. However, this does not affect the object outside the method because the parameter is passed by value of the reference, but the reference itself is copied.
6. Prints a.val — the output will still be 2.

Final output:

2
2

Explanation:

• In Java, objects are passed to methods by value of the reference. That is, a copy of the reference to the object is passed.
• In the inc method, the field of the object that a refers to is modified, so the changes are visible outside the method.
• In the set method, the reference a is reassigned to a new object, but this is a local change to the reference and does not affect the original object outside the method.