Strings

[jose chiramal]

    class Test2
{
public static void main (String args [])
{
String s1 = "Hello";
String s2= s1;
System.out.println(s1 + "equals" + s2 + s1.equals(s2));
System.out.println(s1 + "==" + s2 + (s1 == s2));

s1 = s2;
System.out.println(s1 + "==" + s2 + (s1 == s2));
System.out.println("value of s1" + s1);
System.out.println("value of s2" + s2);

s2= null;
System.out.println("value of s1" + s1);
System.out.println("value of s2" + s2);
System.out.println(s1 + "==" + s2 + (s1 == s2));
}

Output :

HelloequalsHellotrue
Hello==Hellotrue
Hello==Hellotrue
value of s1Hello
value of s2Hello
value of s1Hello
value of s2null // how ??? arent s1 and s2 pointing to the same location ?
Hello==nullfalse // how ???

[Pramod P Deore]

sorry I post this in wrong forum

[Pramod P Deore]

You have assigned null to s2 at line 15. It does not affect s1

[Yogesh Gnanapraksam]

Are you expecting a null pointer exception in this line ?
s1 == s2

It is other way of checking whether a string is null

if (s1==null) --> false

it works as expected....

[Rob Spoor]

jose chiramal wrote:value of s2null // how ??? arent s1 and s2 pointing to the same location ?

Well, not anymore. You let s2 point to a different location, to be precise no location at all.

[jose chiramal]

I have a similar question below

public static void main(String[] arguments) {

int a = 1,b=2;
Test7 t1 = new Test7(a,b);
int a1 = 3,b1=4;
Test7 t2 = new Test7(a1,b1);
System.out.println("t1: " + t1.a + ", " + t1.b);
System.out.println("t2: " + t2.a + ", " + t2.b);
System.out.println("t1 equals t2 ???" + t1.equals(t2));
System.out.println("t1 == t2 ???" + (t1==t2));
t1=t2;
t2.a = 100;
t2.b = 100;
System.out.println("t1: " + t1.a + ", " + t1.b);
System.out.println("t2: " + t2.a + ", " + t2.b);
System.out.println("t1 equals t2 ???" + t1.equals(t2));//here we have equals as true , then in the case of : String s1 = "Hello";   
//String s2=s1;  s2= null;  why does s2 point to a different location, anything special with null ???

System.out.println("t1 == t2 ???" + (t1==t2)); 
}

[Campbell Ritchie]

Yes, of course null is a different location.