Styjun

I need to write a program which defines two arrays of ints and prints all elements of the first array which do not appear in the second, but each value once only, without repetitions (the order of printed values is irrelevant).
For example for arrays

 int[] arr = 4,3,4,3,6,7,4,8,2,9 ;
 int[] brr = 2,3,6,8,1,5 ;

the result could be :
7 4 9

It can be used only java.lang. package. It can't be created any arrays, collections or Strings.

This prints all elements of the first array which do not appear in the second, now you just have to check for repetitions.

 public static void compareArrays(int[] arr1, int[] arr2) 

 boolean equal = false;
 int[] printed = null;

 for (int i = 0; i < arr1.length; i++) 
 for (int x = 0; x < arr2.length; x++) 
 if (arr1[i] == arr2[x]) 
 equal = true;
 break;
 else 
 equal = false;
 
 
 if (equal != true) 

 System.out.println(arr1[i]);
 
 
 

 public static void main(String[] args) 
 int[] arr = 4, 3, 4, 3, 6, 7, 4, 8, 2, 9;
 int[] brr = 2, 3, 6, 8, 1, 5;

 compareArrays(arr, brr);
 

I will give you some pointers, but will not provide any code as I've not seen any attempt from your side. You can tackle this problem several ways, have a look and try to implement this yourself. You will learn much more during the process, rather than if someone gives you a complete full-code answer. So here goes:

First method:

1. Create a new ArrayList that will hold your output.


2. Iterate through the first array, iterate through the second array. Compare each value.


3. If value is not present and is not present in the output list (you would need to check for that specifically, so you dont have repetition of values), then add it to output list.


4. Print output list.

Second method:

1. Convert both arrays into an ArrayList.




2. Use the removeAll() method provided with Lists to get difference between the arrays. This will be stored in one of the lists you created earlier.




3. Remove repetitive items from the list (e.g. using Streams).

Third method:

1. Create a new ArrayList that will hold your output.




2. Iterate through values of array1.




3. Initialize a boolean variable (e.g. call it contains) that will determine whether a value from array1 is present in array2 using an IntStream.




4. Create if statement - if contains is true, add the value to your output list. Check that your output List already doesn't have the value and only add if it doesn't. Print output list.

Something like this:

String[] unique = new HashSet<String>(Arrays.asList(arr)).toArray(new String[0]);

for (int uEach : unique) 
 for (int bEach : brr) 
 if (unique[uEach] == brr[bEach]) 
 ArrayUtils.removeElement(unique, uEach);
 
 
;

System.out.print(unique);

 static void findMissing(int a[], int b[]) 
 
 for (int i = 0; i < a.length; i++) 
 
 int j; 

 for (j = 0; j < b.length; j++) 
 if (a[i] == b[j]) 
 break; 

 if (j == b.length) 
 System.out.print(a[i] + " "); 
 
 

You can use to get distanct value from an array

int[] unique = Arrays.stream(arr).distinct().toArray(); 

then loop over both arrays and match strings if not found print that

 int i,j,occ;
 int[] arr = 4,3,4,3,6,7,4,8,2,9 ;
 int[] brr = 2,3,6,8,1,5 ;
 arr = Arrays.stream(arr).distinct().toArray();
 for( i =0; i < arr .length; i++)
 occ = 0;
 for( j =0; j < brr.length; j++)
 if(arr [i] == brr[j])
 occ ++;
 
 
 if(occ==0)
 System.out.println(arr [i]);