Java StringBuffer capacity()  method returns the current capacity. The capacity is the amount of storage available for newly inserted characters, beyond which allocation will occur.

Java StringBuffer capacity() Example

Example: This simple program demonstrates the usage of capacity() method.

public class CapacityExample {
 public static void main(String[] args) {
  StringBuffer builder = new StringBuffer("javaguides");
  int capacity = builder.capacity();
  
  // inital capacity
  System.out.println(new StringBuffer().capacity());
  
  // intial capacity 16 + number of characters in string
  System.out.println("Capacity of the string :: " + capacity);
 }
}

Output:

16
Capacity of the string :: 26

Reference

https://www.javaguides.net/2018/08/stringbuffer-class-methods-in-java.html