Why people use new String instead of certain value?

Question

Simple code:

class MyClass<T>
{

private T t;

    public void add(T t)
    {
       this.t = t;
    }

    public T get()
    {
     return t;   
    }  
}

And then:

public static void main(String[] args) {

    MyClass<String> StringClass = new MyClass<>();

    StringClass.add("This is string");

 // **Or actually it can be:  StringClass.add(new String("This is string"));**

I saw that people use StringClass.add(new String("This is string")) instead of simple version StringClass.add("This is string"). What's the difference?

Same story with Integers.

Also note that java naming conventions states that variable names should start with a lowercase character. — Sotirios Delimanolis, Oct 24 '13 at 17:18
But this code works in both versions. The result is the same. So what's the difference? — Ernusc, Oct 24 '13 at 17:20

An SO User · Accepted Answer · 2013-10-24T17:25:57.950

1

The difference between
String foo = "bar"

and

String foo = new String("bar")

is that the first one does not create a new String object but rather, it looks for that value in the existing String values that you have created. This is called interning the value. This saves memory.

The one with the new keyword assigns new memory for the String object you created.

public class StringInternExample {
    public static void main(String[] args) {
        String foo1 = "bar";
        String foo2 = "bar";

        String foo3 = new String("Hello, Kitty");
        String foo4 = new String("Hello, Kitty");

        if(foo1 == foo2){ // compare addresses. Same address = no new memory assigned
            System.out.println("No new memory has been assigned for foo2");
        }

        if(!(foo3 == foo4)){ // compare addresses. Different addresses = new memory
            System.out.println("New Memory has been assigned for foo4");
        }

    }
}

edited Oct 24 '13 at 17:25

answered Oct 24 '13 at 17:19

An SO User

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The main difference between these two methods is that the former tries to re-use an existing string from the string pool, whereas the latter explicitly creates a new one. – Jeroen Vannevel Oct 24 '13 at 17:20
1

They are not the same. – Sotirios Delimanolis Oct 24 '13 at 17:21
Definitely not the same. – Mike Christensen Oct 24 '13 at 17:21
@SotiriosDelimanolis and the SSCCE has loaded 100%. – An SO User Oct 24 '13 at 17:30
1

http://stackoverflow.com/questions/3297867/difference-between-string-object-and-string-literal – Nir Alfasi Oct 24 '13 at 17:31
1

Thanks! So the point is not to create new object of string. – Ernusc Oct 24 '13 at 17:33

Why people use new String instead of certain value?

1 Answers1