Thinking of different solutions to String repeat challenge.

I was doing some CodeWars challanges and this looked interesting:

Write a function that accepts an integer n and a string s as parameters, and returns a string of s repeated exactly

initially my guess is to brute force this challenge to just append things:

Some of the solutions:

• Stringbuilder

  sb.append(string);
  

• Simple Strings

  s += string
  

• String methods (java 11)

  string.repeat(repeat);
  

which is the best?