Given an array of size N in which every number is between 1 and N, determine if there are any dupli

Given an array of size N in which every number is between 1 and N, determine if there are any duplicates in it.

import java.util.Arrays;
 import java.util.HashSet;
 import java.util.Set; public class Duplicate {
 
  public static boolean duplicate1(int[] number,int N){
   Set s=new HashSet();
   for(int i=0;i<N;i++)
   s.add(number[i]);
   if(s.size()<N)return true;
   else return false;
  } 
  
  
  public static boolean duplicate2(int[] number,int N){
   Arrays.sort(number);
   for(int i=0;i<N-1;i++)
   {
    if(number[i]==number[i+1])return true;
   }
   return false;
  }
  
  
  
  public static void main(String args[]){ 
   int N=3;
   int[] number=new int[N];
   for(int i=0;i<N;i++)
   {
    number[i]=(int)(Math.random()*N);  
       System.out.print(number[i]+" ");
   }
   
   System.out.println(duplicate1(number,N));
   
   System.out.println(duplicate2(number,N));
   
   
  }
 }