Why String is Immutable in Java?

Whats the use intern() method in String class? String s1=“Hello”; String s2=new String(“Hello”); System.out.println(s1==s2); // this is shows output false s2=s1.intern(); System.out.println(s1==s2); // this gives output true, Can u explain how it works?

- siddu

String str=new String(“Hello”); How many objects are created in this case ? String “Hello” passed as argument where is it stored ?

- Arunda

String s1 = “ABC”;-- This goes to pool directly String s2 = new String(“ABC”);–according to ur one of answers above , this created 2 objects, 1 in pool and another in heap memory. I am little confused. So when we check as below s1==s2, then it gives false as s2 refrers to heap area. so, what happens to the reference to the pool area as object is created there also.

- Ankush Raina

Hi Pankaj, One query based on String immutability feature ,what is better to store a password charArray or String ?

- Sonam Devikar

Hi Pankaj, You mentioned that String is immutable because the hashcides are cached during creation. I didn’t get the meaning of it. Could you please explain?

- Sudha

Thats a great point about a `String` object being an excellent key for `HashMap`s. Had never thought about that before…

- Akshayraj A Kore

I have one question ad String used for security purpose so none can modify secure data…But my question is if we assign new value in already created String then older secured data does not have any reference…Because that occupied by new string…Then how is it secure?

- Santosh Gupta

String s1=”Hello”; String s2=new String(“Hello”); System.out.println(s1==s2); Will above two strings will be true post Java 7, as string pool moved to Heap area ?

- Rohit

Refer the below code : public class StringImmutable_Test_1_0 { public static void main(String args[]){ String s1 = new String(“nilakshi”); String s2 = “harshada”; String s3 = “nilakshi”; s1 = “harshada”; if(s1 == s2) System.out.println(“s1 and s2 has same reference”); else System.out.println(“s1 and s2 doesn’t have same reference”); s1 = new String(“nilakshi”); if(s1 == s3) System.out.println(“s1 and s3 has same reference”); else System.out.println(“s1 and s3 doesn’t have same reference”); } } This gives me output as follows --> s1 and s2 has same reference s1 and s3 doesn’t have same reference Why this is giving me such result although string is immutable ?

- Nilakshi Patil