Question

I have a private int array, and I need to somehow find the length but I cannot do this under the static class. I have to keep the class static, is there another method I can add to change a.length to something else?

The issue is caused by a.length.

private int [] a;

public static IntegerSet union(IntegerSet otherSet, IntegerSet nextSet) {

                for(int i=0; i<a.length; i++) {
                  if (otherSet.isSet(i))
                    nextSet.insertElement(i);
                }

                return nextSet;
              }

Answer 1

As i said use

public int lenghtOfArray(){
      return this.a.lenght;
}

and change your method to

public static IntegerSet union(IntegerSet otherSet, IntegerSet nextSet) {
      for(int i=0; i<otherSet.length(); i++) {
           if (otherSet.isSet(i))
                nextSet.insertElement(i);
           }
           return nextSet;
      }