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 String toString( ) 
    {
        StringBuilder sb = new StringBuilder( "[" );

        for( int i = 0; i < theSize; i++ )
            sb.append( " " + items[ i ] );

        sb.append( " ]" );

        return new String( sb );
    }

    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;
    }

    ...
}