How many objects are created by String code?

Puzzle:

String s1 = "abc";
String s2 = new String("abc");
String s3 = s2.toUpperCase();

Answer: 3 objects.

1. • Created in the String Constant Pool (if not already there).
2. new String("abc") - Created in the Heap.
3. s2.toUpperCase() - Creates a new String "ABC" in the Heap because Strings are immutable.

Another Puzzle:

String s = "Hello";
s.concat("World");
System.out.println(s);

Output: "Hello" Objects: 3 created ("Hello", "World", "HelloWorld"), but s still points to "Hello".