Set intersect print error

Question

I am trying to build a Set for myself, with just intersect,union and print as the methods.

my test code is

public static void main(String[] args)
{
    double[] a = {1,2,3,4,101.9};
    double[] b = {3,7,13,901,-29.1,0.0001};

    NumSet test;
    test = new NumSet(a);
    test.intersect(a, b);
    System.out.println("tried intersect [1,2,3,101.9], [3,7,13,901,-28.8,0.001]");
    test.print();
    System.out.println("tried test.print()");
    test.union(a,b);
    System.out.println("tried union [1,3,3,5,7,9], [3,5,7,13]");
}

which gives me an

tried intersect [1,2,3,101.9], [3,7,13,901,-28.8,0.001]
0.0,0.0,0.0,out of bounds 4 >= 4 or 4 < 0 
0.0tried test.print()
tried union [1,3,3,5,7,9], [3,5,7,13]

which is strange, because my print has nothing to do with printing such a sentence as the second one.

public void print() 
{
    for (int i = 0; i < set.size() - 1; i++)
    {
        System.out.print(set.lookup(i) + ",");

    }
    System.out.print(set.lookup(set.size()));
}

this is my print method. and as the class is extending another class,

public class NumSet extends NumArrayList
{
NumList set;

    public NumSet(double[] sth)
    {
        set = new NumArrayList();
        for (int i = 0; i < sth.length; i++)
        {
            set.insert(i, sth[i]);

        }
        set.removeDuplicates();
    }



int numSet = 0;

public NumList intersect(double[] S1, double[] S2)
{
    for (int i = 0; i < S1.length; i++)
    {
        for(int j = 0; j < S2.length; j++)
        {
            if (S1[i] == S2[j])
                {
                set.insert(numSet, S1[i]);
                numSet++;           
                }
        }
    }

    set.removeDuplicates(); 
    return set;

}

public NumList union(double[] S1, double[] S2)
{
    for (int i = 0; i < S1.length; i++)
    {
        set.insert(1, S1[i]);
    }

    for (int i = 0; i < S2.length; i++)
    {
        set.insert(1, S2[i]); 
    }
    set.removeDuplicates();
    return set;
}

I went and checked the print method there.

public void print()
{
    for (int i = 0; i < numItems - 1; i++)
    {
        System.out.println(items[i]+ ",");
    }
    System.out.println(items[numItems-1]);

}

which leaves me dumbfounded as to why my error message is as such.

Where is my print referring to to get such a weird message?

Answer 1

You're missing a -1 in your last print statement:

System.out.print(set.lookup(set.size()));

should be:

System.out.print(set.lookup(set.size() - 1));

Remember that lookup indexes are zero-based, so using set.size() is indeed out of bounds.