pass by reference- Swapping problem

[Anil Deshpande]

This the program i have written to Swap the person Object. I know why it is not working. Because java always does pass by value.
Even for objects. But I really want to swap it. What can be done in the swap method?

The program is as follows.

  
public class Person {
	
	private String name;
	
	
	public Person() {
		// TODO Auto-generated constructor stub
		super();
	}
	
	public Person(String name)
	{
		this.name=name;
	}
	
	@Override
	public String toString() {
		// TODO Auto-generated method stub
		return name;
	}
	
	
	
	public static void swap(Person person1,Person person2) {
		
		
		Person p=person1;
		person1=person2;
		person2= p;
		
		System.out.println("Inside the swap method");
		
		System.out.println(person1);
		System.out.println(person2);
		
	}

	
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		Person person1=new Person("Anil");
		Person person2=new Person("Ajay");
		
		System.out.println(person1);
		System.out.println(person2);
		Person.swap(person1, person2);
		
		System.out.println("After Swapping");
		
		
		System.out.println(person1);
		System.out.println(person2);
		
		

	}

}
  

and the out put is as follows

Anil
Ajay
Inside the swap method
Ajay
Anil
After Swapping
Anil
Ajay

[Steve Luke]

Anil Deshpande wrote:This the program i have written to Swap the person Object. I know why it is not working. Because java always does pass by value.
Even for objects. But I really want to swap it. What can be done in the swap method?

The method can't be made to swap them. So what do you need the swap method for? Sorting? Or just for show/proof of concept?

[Rob Spoor]

You can use a two element array, and swap the array elements.

[Campbell Ritchie]

The rules about pass-by-reference in Java are easy to remember . . .

There is no such thing as pass-by-reference. Look at this FAQ.

[Anil Deshpande]

Got It. Story is very good. Thanks a lot

[Campbell Ritchie]

You're welcome

[santhosh.R gowda]

Way too many people say "Java passes primitive by value and objects by reference". This is not the way it should be stated. Java passes everything by value. With primitives, you get a copy of the contents. With references you get a copy of the contents.