java - hashCode method called for System.out.println() method in HashSet -

import java.util.hashset; import java.util.set;     class employee {     @override       public int hashcode() {     system.out.println("hash");     return super.hashcode();     }  }   public class test2 {  public static void main(string[] args) {     set<employee>set= new hashset<>();     employee employee = new employee();     set.add(employee);     system.out.println(set);// if comment "hash" printed once }  } 

above code calls hashcode method 2 times if print set. why hashcode method called on system.out.println()?

see this. in short, default tostring() function calls hashcode() , uses hexadecimal representation of hash part of string.