CareerCup

Java?

I would hope the compiler converts this to bytecode roughly equal to
String temp = "ABC";

It's all known at compile time.

What version of Java?

I agree, modern compiler should convert String to StringBuilder. String literals are pooled in String pool.

why it won't be 4?

I think the answer will be 4.
1. "A"
2. "B"
3. "C"
4. temp

Four Objects of String type are created: A, B and C and ABC

5 Objects will be created
A, B, C, AB, ABC

Between 0 to 5. String literals are in the string literal pool, so these strings ("A", "B", "C", "AB", "ABC") are created only if they are not in the pool.

5Object will create here.....A,B,C,AB,ABC

Khusabhukumare

5 object will create "A" "B" "C" "AB" "ABC" because the string object created and string concatinate

5 object will create "A" "B" "C" "AB" "ABC" because the string object created and string concatinate