Java and Database Connectivity

A bit about syntax: declaring a constructor

A constructor is a special method called to construct an instance of a class. It has the same name as the class, and no return type declaration

    /** initialise myself; in addition to the things hands have
     *  generically, I have a radius */

Again, a 'javadoc' comment. This one documents this constructor.

    public BlobHand( int l, HandDriver d, int r)

This constructor takes three arguments, respectively an int, a HandDriver, and another int. An int is a primitive data type which is not an object; a HandDriver is an object whose class is either HandDriver or some subclass of HandDriver

    {
        super( l, d);

The first thing this constructor does is to pass it's first two arguments 'up the tree' to its superclass's constructor, which knows how to deal with them.

        radius = r;
    }

The superclass doesn't have a radius, so it can't know how to deal with it. So initialise it here.

Full text of this presentation | Table of Contents | No Frames Author: Simon Brooke | Copyright © 2001 Simon Brooke Slide 34 of 95

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