how many objects are created?

[Bin Wang]

How many objects are created by the following code?
1. StringBuffer s1 = new StringBuffer("abc");
2. StringBuffer s2 = s1;
3. StringBuffer s3 = new StringBuffer("abc");
Answer given is: 3
Can somebody explain?

[Junilu Lacar]

s1 references a StringBuffer (object #1)
s2 references same StringBuffer referenced by s1
s3 references a StringBuffer (object #2)
"abc" is created in the string pool (object #3)

[Jyotsna Umesh]

Originally posted by JUNILU LACAR:
s1 references a StringBuffer (object #1)
s2 references same StringBuffer referenced by s1
s3 references a StringBuffer (object #2)
"abc" is created in the string pool (object #3)

I thought object can be created through 'new' only, can you please explain why "abc" is an object and inthe code if we change
line 3 as StringBuffer s3 = new StringBuffer("xyz"); so will there now be 4 objects?
Thanks in advance
Jyotsna

[Junilu Lacar]

Strings are objects, regardless of whether they are in the string pool (as a string literal) or in the heap (as an object created by new). See Dave Vick's post referencing the JLS in this thread: http://www.javaranch.com/ubb/Forum24/HTML/010491.html

[Junilu Lacar]

One thing that might convince you that string literals are objects is the fact that you can write this:
<pre>
void test( String s ) {
if ( "This is an Object".equals(s) )
System.out.println("It works!");
}
</pre>


[This message has been edited by JUNILU LACAR (edited June 28, 2001).]

[Hassan Naqvi]

Hi Junilu,
According to me only two objects are created one by s1 & another by s2.Whereas s2 is referencing the same object as s1.
Can you explain more that how 3 objects are created.
Regards,
Hassan.

[Junilu Lacar]

Hassan,
Kindly hit your browser's refresh button so you can see the previous replies above which I hope will clearly explain why 3 objects are created, not 2.

[Hassan Naqvi]

Hi Junilu,
Now no need for pressing refresh button.The link you give defines well & deeply..
Regards,
Hassan.