Part (a)

package cop3530;

public interface Set
{
    boolean isEmpty( );
    boolean contains( Object obj );
    int size( );
    
    void makeEmpty( );
    boolean add( Object obj );
}


Part (b)

package cop3530;

import java.util.Comparator;

public class SortedArraySet implements Set
{
    private int theSize;
    private Object [ ] items;
    private Comparator cmp;
    
    public SortedArraySet( )
    {
        this( new DefaultComparator( ) );
    }
    
    private static class DefaultComparator implements Comparator
    {
        public int compare( Object lhs, Object rhs )
        {
            return ((Comparable)lhs).compareTo( rhs );
        }
    }
    

    public boolean contains( Object obj )
    {
        int pos = 0;
        
        while( pos < size( ) && cmp.compare( obj, items[ pos ] ) < 0 )
            pos++;
        
        return pos != size( ) && cmp.compare( obj, items[ pos ] ) == 0;
    }
    
    ...
}