How do I put only unique values into an array?

Question

node_marked_array.add(strings[0]);

for (int i = 0; i < strings.length; i++) {
    for (int a = 0; a < strings2.length; a = a + 2) {
        if (node_marked_array.get(i).equals(strings2[a])) {
            if (!node_marked_array.get(i).equals(strings2[a + 1])) {
                //    System.out.println("marked node: " + node_marked_array.get(i) + "=" + strings2[a] + ", added node " + strings2[a+1]);
                node_marked_array.add(strings2[a + 1]);
            }
        }
    }
}

I have an array named strings2 of elements each being:

1, 2, 1, 3, 2, 3, 2, 4, 3, 2, 5, 5, 2,

and my code is supposed to go through the array and if it matches for example any of the element that is in the array called strings: {1,2,3,4,5} with that of strings2 for each even element. It checks the i+1 element of the array above to see if the element is already added to the marked array, if it isn't then it adds it. However I am seeing duplicate values even with

if (!node_marked_array.get(i).equals(strings2[a + 1]))

output: 1 2 3 3 4 2 5 2 5 5

Answer 1

Use Set. Array is the wrong data type for this problem.

It contains a .toArray() method that will give you back an array after you've constructed the set, if that is what you require.

Answer 2

Use a Set. Starting from your code:

HashSet<String> noDuplicate = new HashSet<String>();
for(int i=0;i<strings.length;i++)
{
  for(int a=0;a<strings2.length;a++)
  {
    if(strings[i].equals(strings2[a]))
    {
      noDuplicate.add(strings[i]);
    }
  }
}

// And then if you need an array:
String[] noDupArray = new String[noDuplicate.size()];
noDuplicate.toArray(noDupArray);