Design pattern - Java creation method

public class CreationMethod {

 public static void main(String [] args){
  Student s1 = Student.createInstance(1);
  Student s2 = Student.createInstance(1, "hello");
  System.out.println(s1.toString());
  System.out.println(s2.toString());
 }
}

class Student{
 int id;
 String name;
 private Student(int id){
  this.id = id;
 }
 
 private Student(int id, String name){
  this.id = id;
  this.name = name;
 }
 
 public static Student createInstance(int id , String name){
  return new Student(id,name);
 }
 
 public static Student createInstance(int id){
  return new Student(id);
 }
 
 public String toString(){
  return id+": "+name;
 }
}