Problem 163.1

Web Addresses

Classes are an easy way to create a single variable that can hold several different values. For example, consider the problem of storing a mailing address. The address has many parts, but is conceptually one unit.

Files Needed: WebAddresses.java

The code provided will create a class called “Address” that contains four fields:

a field for the house number / street name (a String) a field for the city name (a String) a field for the state (a String) a field for the zip code (an int)

The example code creates an instance of the Address class and assigns it to a variable of type Address.

What You Should See

1313 Disneyland Dr, Anaheim, California  92802

What You Should Do on Your Own

Assignments turned in without these things will receive half credit or less.

1. The code provided only creates one Address object. Change the code to create and print out two more Address objects.

Clarifications

Class

A class is a general template or prototype for an object. Classes define the general attributes and behaviours for any objects we may need in our program.

If we think about a human class, in general, every human has:

• a name
• a birthdate
• weight
• height

Humans obviously have other attributes but, those will do for now.

class Human {
  String name;
  Date birthdate;
  double weight;
  double height;
}

Object

An object is a specific instance of a class. You are a specific instance of the human class. Every object has specific data stored in it.

We can create a new object by using the familiar new keyword in Java.

Human someHuman = new Human();

We can the assign specific values to each of the object’s attributes.

someHuman.name = "Mr. Gallo";
someHuman.weight = 72.5;
someHuman.height = 172;

We can access these attributes the same way we set them.

System.out.println("This human is " + someHuman.height + "cm tall.");

It is like using Arrays, except rather than using [] to reference a particular piece of data, we use “dot notation” and use a descriptive name for the data being referenced. This makes our code much easier to read.