1.

package cop3530;

public interface List<AnyType>
{
    boolean contains( AnyType x );
    int size( );
    boolean isEmpty( );

    void add( AnyType x );
    void clear( );
}


2.

package cop3530;

public class ArrayList<AnyType> implements List<AnyType>
{
    private AnyType [ ] items;
    private int theSize;

    public ArrayList( )
    {
        items = (AnyType []) new Object[ 5 ];
        theSize = 0;
    }

        // Required for Version A only
    public boolean contains( AnyType x )
    {
        for( int i = 0; i < theSize; i++ )
            if( items[ i ].equals( x ) )
                return true;

        return false;
    }

        // Required for Version B only
    public void add( AnyType x )
    {
        if( theSize == items.length )
        {
            AnyType [ ] old = items;
            items = (AnyType []) new Object[ old.length * 2 + 1 ];
            for( int i = 0; i < old.length; i++ )
                items[ i ] = old[ i ];
        }

        items[ theSize++ ] = x;
    }

    ...
}