String class in java

Question

In java String is a class and it is imutable so we can not change its value.In following code it will concate other string without any error.So I want to ask that if it is immutable then why in this following code value of String is changed??

import java.util.*;

public class conc
{
    public static void main(String args[])
    {
        String a="Sheetal";
        a=a+"Ga";
        System.out.println("Result:"+a);
    }
}

Because it's not a reference to the original `String` object? — August, Aug 01 '14 at 07:26
`a = a + "Ga"` is actually creating an entirely "new" instance `String`. Try printing the `hashcode` of `a` before and after the assignment ;). Also try `String b = a + "Ga"` and print out both `a` and `b`... — MadProgrammer, Aug 01 '14 at 07:26
You are correct , If you are not assigning with a new String :) — Suresh Atta, Aug 01 '14 at 07:35
take some time reading about Strings and if you must ask a question, try researching existing questions in SO first, prior to asking such basic questions. — Pat, Aug 01 '14 at 08:00

score 6 · Accepted Answer · answered Aug 01 '14 at 07:27

In the code that you have shown, you have not changed the original String object.

Instead, you have created a new String object, which represents a + "Ga", and then re-assigned it to the reference variable a.

Note that all variables in Java other than primitive types are references.

Pablo Francisco Pérez Hidalgo · Answer 2 · 2014-08-01T07:38:50.110

6

You are creating a new object by concatenating two strings, that is: You are not changing the object referenced by a but assigning to that reference the value referencing to a new String object.

edited Aug 01 '14 at 07:38

answered Aug 01 '14 at 07:27

Pablo Francisco Pérez Hidalgo

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Ruchira Gayan Ranaweera · Answer 3 · 2014-08-01T08:02:46.567

0

 String a="Sheetal";
        a=a+"Ga"; // now this is not the same object you are referring early

When you alter your a will create a new String.

Your original String is not change that's why we call String are immutable and new String will create in the heap.

In this moment there are 2 object in your heap. now a is referring new Object.

edited Aug 01 '14 at 08:02

answered Aug 01 '14 at 07:27

Ruchira Gayan Ranaweera

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Where are your reason to downvote?. Is this not provide answer? who are the people downvote this??? mentally ill or any other issue – Ruchira Gayan Ranaweera Aug 01 '14 at 07:31
Now `stackOverFlow` become senseless. – Ruchira Gayan Ranaweera Aug 01 '14 at 07:39
1

It seems like those downvotes are caused by your english, sorry, but it's hard to understand what you mean :( – krems Aug 01 '14 at 07:59
@krems ohh my English is that much bad? :(. BTW thank for your comment. Now I know at least a possible reason to downvote. See people please use to put a comment when you downvote. It will help all of us. – Ruchira Gayan Ranaweera Aug 01 '14 at 07:59
What moderator says about downvote-: `There's no requirement to give reasons for down-votes` nice – Ruchira Gayan Ranaweera Aug 01 '14 at 08:06
@RuchiraGayanRanaweera Stackoverflow would be a lot better if a reason would be mandatory to down vote instead the -2 points penalization. – Pablo Francisco Pérez Hidalgo Aug 01 '14 at 08:44
@PabloFranciscoPérezHidalgo yes. It is. – Ruchira Gayan Ranaweera Aug 01 '14 at 08:45

String class in java

3 Answers3