String and int behavior based on assignment

[Chinmoy Padhi]

Hi JavaRanch,
I have came across a code and below are my queries based on the output of the program

1. what does 1st two system.out.println() means?
2. If String class is immutable then how

d.s = "seed"

is possible ?
3. How int value didn't get changed when it has been assigned with

new Project().i=50;

?

package com.sanujava;

public class Project 
{
	int i=10;
	String s="sid";//instance variables

	public static void main(String[] args) 
	{
		Project d=new Project();
		System.out.println("value of i is "+new Project());
		System.out.println("value of s is "+new Project());
		
		System.out.println("*************");
		

		d.i = 70;
		d.s = "seed";
		
		System.out.println("+++++++++++++++");
		
		System.out.println("value of d.i:"+d.i);
		System.out.println("value of d.s:"+d.s);
		
		new Project().i=50;
		new Project().s="seeder";
		
		System.out.println(new Project().i);
		System.out.println(new Project().s);
		

	}

}

Output of the program
--------------------------
value of i is com.sanujava.Project@1db9742
value of s is com.sanujava.Project@106d69c
*************
+++++++++++++++
value of d.i:70
value of d.s:seed
10
sid

[Henry Wong]

Chinmoy Padhi wrote:
1. what does 1st two system.out.println() means?

The first two println() doesn't do what it claims. It is supposed to print the value of "i" and "s", but it just creates a new Project object to be printed. And since the Project class never overridden the toString() method, those two calls yield the first two printouts with the identity hash values of those objects.

Henry

[Liutauras Vilda]

Henry already answered to your first question.

Second and third question have nothing to do with strings immutability.

2.
On the line 8 you have created Project object which is being refered to by the variable "d".
On line 15 and 16 you reassign Project class instance variables which were declared and initialized on lines 3 and 4.

3.
On line 23 and 24 you're creating new Project objects and printing their instance field values, which are declared and initialized again on lines 3 and 4, and these values are "10" and "sid".

[Liutauras Vilda]

And welcome to the  Ranch

[Ganesh Patekar]

One click here --> Strings, Literally by Corey McGlone  and couple of minutes of perusing it might clear all your doubts of String in Java.

[fred rosenberger]

and remember...a String is immutable. But a reference to a string can be directed to point to a different String.