difference between null string and ""

[saikrishna cinux]

1.String s=""
2.String x=null

is 1& 2 are same??
cinux

[Christophe Verré]

There are not the same.

String s = ""; would be the same as String s = new String("");
You are implicitly instanciating a new String variable.

In your example, try to call s.length() and x.length()
[ January 10, 2006: Message edited by: Satou kurinosuke ]

[saikrishna cinux]

It's ok but if run the below program it perfectly executes with out error saying that s is not initialized with string value.

public class Test
{
public static void main(String[] args) throws Exception {
step1 String s="";
step2 //String s2;//leads to compile time error because no value is initialized

System.out.println(s.length());

}
}

I think step1 an step2 are same. :roll: :roll:

[Jeff Albertson]

public class Test {
    public static void main(String[] args) {
        String s = "";
        String x = null;
        System.out.println("s==x is " + (s==x));
    }
}

[fred rosenberger]

remember that s and x are REFERENCES to objects, not the objects themselves. Think of them as envelopes.

when you say

String s = "";

you are saying "I want an envelop, and put an adress on the envelope, even though nobody lives at that address."

when you say

String x = null;

you are saying "i want an envelope with NO address on it."

if you mail the first envelope, it'll go somewhere. the second one will confuse the post office.

[Keith Lynn]

Originally posted by saikrishna cinux:

I think step1 an step2 are same. :roll: :roll:

No, they are not the same. s is referring to a valid String object that has no characters in it. s2 is referring to nothing.

[Corey McGlone]

Originally posted by fred rosenberger:
if you mail the first envelope, it'll go somewhere. the second one will confuse the post office.

Not often does tech talk make me laugh, but this sure did.

Nice analogy.

[Matti Poro]

You can get the program to be compiled if you write:
String x = null;

But of course then x.length() will throw a NullPointerException if you run the program.

[marc weber]

Originally posted by fred rosenberger:
...if you mail the first envelope, it'll go somewhere. the second one will confuse the post office.

Very nice.

[saikrishna cinux]

Originally posted by fred rosenberger:
remember that s and x are REFERENCES to objects, not the objects themselves. Think of them as envelopes.

when you say

String s = "";

you are saying "I want an envelop, and put an adress on the envelope, even though nobody lives at that address."

when you say

String x = null;

you are saying "i want an envelope with NO address on it."

if you mail the first envelope, it'll go somewhere. the second one will confuse the post office.

My dear fred u really Rock!!! explained it in a gr8 way..
keep it up ..
and thanks a lot
bye