Using Array.length with duplicate values in an array

Question

If i have an array with say 4 values, and all the values are the same. Is it possible to use something like array.length or size, so that the length returned is only 1.

You would need to create a static helper method somewhere that takes the array as an argument. In Java you can't add new methods or overwrite methods on the array object. — JustinKSU, Jun 26 '18 at 16:15

score 2 · Accepted Answer · answered Jun 26 '18 at 16:19

use something like below and remove the Duplicate Element in your array and generate set from your array :

Integer[] array = ... Set<Integer> mySet = new LinkedHashSet<Integer>(Arrays.asList(array ))

your array stay untouched and you can find out the size by :

mySet.size()

score 1 · Answer 2 · answered Jun 26 '18 at 16:15

1

Not with the Array API. You have to build a Set of the elements in the array and thus, since the Set can't contain duplicates, it's .size() methods will return 1.

_{(Actually, Set::size() returns the number of distinct elements put in the Set)}

answered Jun 26 '18 at 16:15

Raffaele

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score 1 · Answer 3 · answered Jun 26 '18 at 16:16

You could try using Map with handles unique values?

Or make an static util class where you parse the array and find the unique values and return the number of them.

But the simplest way is, uniquest values from a Integer array list, from here:

Integer[] numbers = {1, 1, 2, 1, 3, 4, 5};
Set<Integer> uniqKeys = new TreeSet<Integer>();
uniqKeys.addAll(Arrays.asList(numbers));
System.out.println("uniqKeys: " + uniqKeys);

score 1 · Answer 4 · answered Jun 26 '18 at 16:18

For non-primitive array, you can create a set and return the size of this set:

Integer[] array = new Integer[4];
array[0] = 1;
array[1] = 1;
array[2] = 1;
array[3] = 1;
Set<Integer> set = new HashSet<>(Arrays.asList(array));
System.out.println(set.size()); //1

score 1 · Answer 5 · answered Jun 26 '18 at 16:19

1

java.util.List or java.util.Arrays doesn't provide a functionality like this but you can use the Stream-API to get something similar:

int nrOfUniqueElems = Arrays.stream(myArray).distinct().count();

answered Jun 26 '18 at 16:19

Lothar

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score 1 · Answer 6 · answered Jun 26 '18 at 16:22

1

You can use the following code sample to get it done in 1 line

new HashSet(Arrays.asList(<your-array-object>).size();

answered Jun 26 '18 at 16:22

Parth Kansara

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score 0 · Answer 7 · answered Jun 26 '18 at 17:18

You can run a for loop that will add elements to another array if the elements are unique, and if they are the same as the other array elements, they will not be added to the new array. Here is an example:

public class ChapterOneBasics {

      public static void main(String[] args){

      int ar[] = {1, 1, 1, 1};
      int ar2[] = {1};

      for(int x = 0; x <= ar.length; x++) {
          if(x > 0) {
               if(ar[x] != ar[x - 1]) {
                     ar2[x] = ar[x];
            }
        }
    System.out.println(ar2.length + " is the size of the array uniqueness.");
      }
   }
}

output:

1 is the size of the array uniqueness.

Using Array.length with duplicate values in an array

7 Answers7