Questions about Java's String pool [duplicate]

Answer 1

In bytecode, the first assignment is:

  Code:
   0:   ldc     #2; //String abc
   2:   astore_1

whereas the second is:

   3:   new     #3; //class java/lang/String
   6:   dup
   7:   ldc     #2; //String abc
   9:   invokespecial   #4; //Method java/lang/String."":(Ljava/lang/String;)V

So the first is in the pool (at position #2) whereas the second will be stored in the heap.

EDIT

Since the CONSTANT_String_info store the index as U2 (16 bits, unsigned) the pool can contain at max 2**16 = 65535 references. In the case you care here more limits of the JVM.