Value & Reference Type

Question

Value Type was kind of confusing
public class MyClass {
public static void main(String[ ] args) {
int x = 5;
addOneTo(x);
System.out.println(x);
}
static void addOneTo(int num) {
num = num + 1;
}
}
// Outputs "5" -> Why the output is 5 I thought was 6?

Answer 1

Java passes by value, and this is a perfect example of that.

int num in the method addOneTo is indeed 5. However this is not the same variable as the one before. num is a new int that has the value of 5.
You then increase the value by one, so num = 6.

But again this is not the same int, num is NOT x. x only passed it's value to the method, which made num equal to that vakue.

To work around this make the function return an int value.

Ex/

int x = 5;
x = addOneTo(x);

Then you can do:
static int addOneTo(int num){
return num+1;
}

In conclusion, In Java, Primitive data-types are passed by value and not by reference.