CODEWITHSUNDEEP
javaarrays
user3390163
user3390163

Reputation: 11

In java,how to check elements in a 1-D array are different to each other?

For example,I have an 1-D array ,how can I check if all the elements are different?(no one same with other,all of them should be different) Use for-loop?Or something else?

I thought maybe this,but cannot be true:

int []array={1,2,3,4,4,6}

for(int i=0;i<a.length;i++){
  if(a[i]!=a[i+1])
    return true;
  else 
    return false;

}

so is there some good method can use to check different?

Upvotes: 0

Views: 101

Answers (4)

Neel
Neel

Reputation: 2100

Set<String> values = new HashSet<>(Arrays.asList(array));
assertEquals(array.length, values.size());

Upvotes: 0

Robin Krahl
Robin Krahl

Reputation: 5308

There are several ways to do this. For example, you can use two for loops:

boolean hasDuplicates(int[] array) {
    for (int i = 0; i < array.length; i++) {
        for (int j = i + 1; j < array.length; j++) {
            if (array[i] == array[j]) {
                return true;
            }
        }
    }
    return false;
}

If that’s too much writing for you, you can just create a Set from the array and compare the size of the set and the array. The set automatically drops duplicate entries.

Upvotes: 0

rgettman
rgettman

Reputation: 178263

Create a HashSet (or another kind of Set), and loop through the elements of your array. Add them one at a time. If the element already exists in the Set, then not all are different and you can return false. You can tell this if add returns false; then you don't have to check the rest of the array. If you finish with the entire array and none are the same, then they're all different and you can return true.

The problem with your current code is that you only check the first and second elements, and you return something right away based on that comparison, and you don't consider the rest of the elements.

Upvotes: 2

Anonymous
Anonymous

Reputation: 71

Add all items from the array into a Set and check the set size with the original array size.

If they're different sizes, then there's a duplicate element.

Upvotes: 7

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