creating array without declaring the size - java

Question

i've digging around about the same issue but i couldn't find the same as i had

i want to create an array without declaring the size because i don't know how it will be !

to clear the issue i'd like to give you the code that i'm looking up for

public class t
{
 private int x[];
 private int counter=0;
 public void add(int num)
 {
   this.x[this.counter] = num;
   this.counter++;
 }
}

as you see the user could use the add function to add element to the array 10000 times or only once so it's unknown size

Answer 1

Using Java.util.ArrayList or LinkedList is the usual way of doing this. With arrays that's not possible as I know.

Example:

List<Float> unindexedVectors = new ArrayList<Float>();

unindexedVectors.add(2.22f);

unindexedVectors.get(2);