java - Finding the union of two arrays -

i'm trying find union of 2 arrays created user input. keep getting:

exception in thread "main" java.lang.arrayindexoutofboundsexception: 4 @ twosets.main(twosets.java:47)

import java.util.scanner;  public class twosets  {  public static void main(string[] args)  {      int i, array, choice;     scanner input = new scanner(system.in);      system.out.print("how many numbers want in each set? ");     array = input.nextint();      int set1[] = new int[array];     int set2[] = new int[array];     int set3[] = new int[array*2];      for(i=0;i<set1.length;i++)     {         system.out.print("enter number first set: ");         set1[i] = input.nextint();     }      system.out.print("\n");      for(i=0;i<set2.length;i++)     {         system.out.print("enter number second set: ");         set2[i] = input.nextint();     }       system.out.print("enter 1 find union\n" + "enter 2 find intersection\n" + "enter 3 find difference\n");     choice = input.nextint(); 

the code above initializing , getting user input, working fine. code below not functioning.

    if(choice == 1)     {         for(i=0;i<array;i++)         {             set3[i] = set1[i];         }          for(i=array;i<array*2;i++)         {             boolean check = union(set2[i], set3);             if(check == false)             {                 set3[i] = set2[i];             }         }         for(i=0;i<set3.length;i++)         {             system.out.print(set3[i]);         }     } }  public static boolean union(int number, int[] array) {     (int : array )     {         if (i == number)         {             return true;         }     }     return false; } } 

the set2 have length of array, in:

for(i=array;i<array*2;i++)         {             boolean check = union(set2[i], set3);             if(check == false)             {                 set3[i] = set2[i];             }         } 

you use array*2 in loop. think bug.