Write a Java program to remove the duplicate elements of a given array and return the new length of the array.

Here is a simple Java program that removes duplicate elements from an array and returns the new length of the array. This program uses a HashSet, which does not allow duplicate elements.

import java.util.HashSet;

public class Main {
    public static void main(String[] args) {
        int[] array = {1, 2, 2, 3, 4, 4, 5, 6, 6, 7};
        int newLength = removeDuplicates(array);
        System.out.println("The new length of the array is: " + newLength);
    }

    public static int removeDuplicates(int[] array) {
        HashSet<Integer> set = new HashSet<>();
        for (int i = 0; i < array.length; i++) {
            set.add(array[i]);
        }
        return set.size();
    }
}

In this program, we first initialize an array with some duplicate elements. We then call the removeDuplicates method, which takes this array as an argument. Inside this method, we create a HashSet and add all elements of the array to this set. Since a set does not allow duplicate elements, all duplicates are automatically removed. Finally, we return the size of the set, which is the new length of the array without duplicates.