Question

I have a question about strings in JAVA

Answer 1

I have this program:
..........
String One = "Hi";
String Two = "Hi";
if(One == Two) {System.out.println("String 1 is equal to String 2");

So, this works. Then why do we use equals() method for finding the equality of strings?

Answer 2

@Abhisar @texaschic101 @ganeshie8 @Zale101

Answer 3

@Zarkon @Destinymasha @sammixboo

Answer 4

@Compassionate @kirbykirby @LolGoCryAboutIt

Answer 5

This is only true in some cases, and is caused by of something called string interning. It's a method used to save space and speed up certain operations.

At compile time each declared string will be created as a constant. After the string constant is created java tries to add the string to a string pool. If there's a string with exactly the same value already present in the pool, the new string won't be added. By doing this we avoid having duplicate string constants.

Interning works because the string object is immutable (a pooled value cannot change). It's possible to perform interning on other immutable as well (although I'm unsure if java does this automatically).

The problem is that interning isn't performed on objects created during runtime, which is why you have to use .equals() and not reference comparison.

Consider the following case:
```
import java.util.Scanner;

class StringTest {
public static void main (String[] args) {
Scanner in = new Scanner(System.in);

String str1 = "foo";
String str2 = "foo";

if (str1 == str2)
System.out.println("Same reference because if interning.");

if (str1 == in.nextLine().trim())
System.out.println("True.");
else
System.out.println("False.");
}
}
```
this returns
```
Same reference because if interning.
False.
```
with std input:
```
foo
```

Runnable example:
http://ideone.com/LJMxZp

You can get more info on this topic at Wikipedia:
http://en.wikipedia.org/wiki/String_interning

Answer 6

Thank you Lyrae

Answer 7

Yw! Anytime ^^