Java Programming - Java.lang Class - Discussion

Let me be more clear you for making you understand the concept of String Objects created. Happy reading.

Case 1> String s1 = new String ("Hello");

String s2 = new String ("Hello");

It will create 2 objects in heap.

Case 2> String s1 = new String ("Hello");

String s2 = new String ("World");

This will create 2 objects in heap.

Case 3> String s1 = new String ("Hello");

String s2 = "Hello";

This will create one object in heap for first line. For second line, it will check whether "Java" exists in string pool or not. If exists, it won't create a new string. It will return the reference to already existing string in pool.

Case 4> String s1 = "Hello";

String s2 = "Hello";

First line will check whether "Java" exists in string pool or not. If exists, it won't create a new string. It will return the reference to already existing string in pool. Second line will get the reference to already created string. So no new objects if "Java" exists or maximum one object.

I hope now this concept is clear to all. :).

String x = new String ("xyz"); /* one object created here "xyz", note: x is a reference variable only */.

String y = "abc"; /* one object created here "abc", note: y is a reference variable only */.

X = x + y; /* one object created here "xyzabc" referenced by existing x variable */.

So, total 3 objects are only created. Do not get confuse between Objects and reference variables.

Proof is:

String x = "xyz";

x == "xyz" false.

Because x referring ingredients of xyz but not to xyz.

And "xyz" is another.

1 line>2.
2> line 1.
3>line 1.

@Anandi.

String is immutable so new object xyzabc is created.

I agree that Line 1 creates 2 object, and 2nd line 1 object but how 4th object is created?

I believe "xyz" is a string literal and not string object. So line creates only one object. Also, as stated, literal "xyz" is not lost as its sitting in the stringpool. "xyz" is not a string object.

Line 2 is also creating another string literal in string pool and its not string object.

Line 3 (concatenation) creates another string object.

So in all - 2 objects - one at line 1 and another at line 3.

Can anyone tell me that why line one creates two object. It should create only one object and this answer is wrong.

Can anyone show the proof that how 4 objects are getting created. I mean is there any way to show to someone on the machine by executing the program.

Please summarize somebody, can we fix the answer as 3 objects.

Please conclude the discussion with proper explanation.

Thanks.

There are only 3 objects will be created because.

In First line,

String x = new String("xyz");

"xyz" an object is created in memory which is referenced by x(reference variable).if u get the hasCode() of "Hello" and x both will be same because x is referenced to "xyz"

String y = "abc";

This line create one object "abc" which is referenced by y;

And finally when,
x = x + y;

A new object is created "xyzabc" which is referenced by x.
String class is an Immutable string so it is not changed a new object is created when concatenation is performed and is referenced by x.