How to calculate String Buffer capacity?

Question

 import java.io.*;

class GFG {

    public static void main(String[] args) {
        StringBuffer s = new StringBuffer("AAA");
        int p = s.length();
        int q = s.capacity();
        System.out.println("Length of string =" + p);
        System.out.println("Capacity of string =" + q);
    }
}

it gives output:

Length of string =3 Capacity of string =19

Actually the length can be found by the number of characters in string,So I know the direct answer without IDE.But what is exactly way to calculate capacity of a string.How can I get an idea of a string capacity without using any IDE.

Answer 1

The capacity is the size of the internal buffer. You usually only care about when you pre-size the buffer for constructing a string you already know the maximum size of. String buffers/builders automatically increase their capacity when they need to.