IsConsecutive.java

package com.company;

import java.util.Arrays;

public class Main {

    public static void main(String[] args) {
        int array[] = {1,2,1,2,3,3};
        System.out.println(isConsecutive());
    }
    
    private static Boolean isConsecutive(int array[]) {
        return Arrays
                .stream(array)
                .mapToLong(Long::new)
                .distinct()
                .sum() == array.length;
    }
}