Implementing the Iterable interface

Question

I just found this exam question in an old exam paper and am readying myself for an upcoming exam. I cannot figure it out :

The following depicts a contrived partial

Answer 1

You can use ArrayIterator, or build your own iterator like this:

package arrayiterator;

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

class ArrayIterator_int
{

    public static void main(String[] args)
    {
        int [] arr = { 5, 4, 3, 2, 1 };

        ArrayIterator_int iterator = new ArrayIterator_int(arr);

        while (iterator.hasNext())
        {
            System.out.println("  " + iterator.next());
        }
    }

    private int cursor;
    private final int [] array;
    private static final Lock lock = new ReentrantLock();

    public ArrayIterator_int (int [] array)
    {
        this.array = array;
        this.cursor = 0;
    }

    public boolean hasNext ()
    {
        boolean hasNext = false;
        lock.lock();

        try
        {
            hasNext = ((this.cursor+1) < this.array.length);
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        finally
        {
            lock.unlock();
            return hasNext;
        }

    }

    public int next () throws ArrayIndexOutOfBoundsException
    {
        int next = 0;
        lock.lock();

        try
        {
            next = this.array[++this.cursor];
        }
        catch(ArrayIndexOutOfBoundsException e)
        {
            throw e;
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        finally
        {
            lock.unlock();
            return next;
        }
    }

    public int read () throws ArrayIndexOutOfBoundsException
    {
        int read = 0;
        lock.lock();

        try
        {
            read = this.array[this.cursor];
        }
        catch(ArrayIndexOutOfBoundsException e)
        {
            throw e;
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        finally
        {
            lock.unlock();
            return read;
        }
    }

    public void write (int newVal) throws ArrayIndexOutOfBoundsException
    {
        lock.lock();

        try
        {
            this.array[this.cursor] = newVal;
        }
        catch(ArrayIndexOutOfBoundsException e)
        {
            throw e;
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        finally
        {
            lock.unlock();
        }
    }

}