How is StringBuffer implementing append function without creating two objects?

Question

It was an interview question. I was asked to implement the StringBuffer append function. I saw the code after the interview. But I cannot understand how the operati

Answer 1

This doesn't compile.

String S= "orange";
S.append("apple");

if you do

final String S= "orange";
final S2 = S + "apple";

This doesn't create any objects as it is optimised at compile time to two String literals.

StringBuilder s = new StringBuilder("Orange");
s.append("apple");

This creates two objects StringBuilder and the char[] it wraps. If you use

String s2 = s.toString();

This creates two more objects.

If you do

String S= "orange";
S2 = S + "apple";

This is the same as

String S2 = new StringBuilder("orange").append("apple").toString();

which creates 2 + 2 = 4 objects.