Java is ' Pass by Value'

Java is pass by value. Here is a simple example to explain the same. 

public class Animal{

public static void main(String a[]){

Dog d = new Dog();

d.type = "Golden Retreiver";

d.setDogType(d);

System.out.println(d.type);

d.setNewDogType(d);

System.out.println(d.type);

}

}

class Dog{

public String type="";

public void setDogType(Dog d) {

d.type="Pug";

}

//Try to change the reference of the existing object

//Surprisingly it does not change...

//It just means java is pass by value and not pass by reference

//The value of reference(memory location) of dog d is passed

//so when u do a new, this change happens in a temporary location

//there is no effect on the calling method object

public void setNewDogType(Dog d) {

d= new Dog();

d.type="Boxer";

}

}

Result: Pug Pug

What happens in the back ground is simple, the address of the memory location is copied to a temporary location which is then used by the called function. So when you modify the object using the passed object will make you feel you are dealing with a reference, but when you try to destroy the old reference and create a new one by using 'new', you just cannot.