Student Handout: Java Programming

Student Handout: Java Programming

Basic Java Methods

Java classes are built from properties and methods. This unit focuses on methods, specifically their naming conventions and the overall syntax used.

A class’s method is simply an action objects of that type can perform. In order to keep the code clear and concise so that you can more easily follow a program’s flow, it is best to write methods that perform a single task, nothing more.

Methods have a declaration, much like a variable, followed by the instructions or commands that actually perform the task. Method names in Java must meet a few requirements:

· Each name must start with a letter.

· The name should be a present-tense verb that matches the task performed.

· The first word in a method name should start with a lower-case letter, and the first letter of each subsequent word in the method name should be capitalized. The name should be followed by a pair of parentheses, which may be empty or may contain parameters.

The following are examples of method names that do not contain parameters:

showValues()
moveCarIntoGarage()
getChocolate()

Methods may invoke other methods. There are examples of this in the Song class.

We will also use two properties. Create a new project called Song. Now add a new class named Song. Open the Song class in the editor and enter the following code. Remember to compile your class as you go along.

/**

* Song.java creates several different methods.

* Each is used from one primary method.

* @author (your name)

* @version (a version number or a date)

public class Song

{

// declare and initialize properties

private String animal, noise;

public void showOldMcD()

{

// show the first part of the song

System.out.println ("Old McDonald had a farm, E I E I O.");

} // end of showOldMcD()

public void showAnimal()

{

// display part about the animal

System.out.print ("And on his farm he had a " + animal);

System.out.println ( ", E I E I O.");

} // end of showAnimal()

public void showNoise()

{

// display part about the animal’s noise

System.out.print ("With a " + noise + " ");

System.out.println ( noise + " here,");

} // end of showNoise()

public void showSong()

{

// set the properties for the first animal

animal = "cow";

noise = "mooooo";

// show each part of the song in order

showOldMcD();

showAnimal();

showNoise();

showOldMcD();

} // end of showSong()

} // end of Song

· Create a new instance of the Song class and test all of the methods

· Compile and test

· Enhance the showNoise() method to show more of that part of the nursery rhyme

· Enhance the showSong() method to display an entire verse of Old MacDonald for at least one animal

· Comment as needed, ensuring that each method includes a description of what it does

· Save, compile, and test often

EXTRAS YOU CAN ADD:

· Get creative and add new animals, sounds, and songs.

Answer the Following Questions:

Essential Question

• What are methods?

Activity Questions

• What is the naming convention for methods?

• What is a void return type?

• What happens if you run showNoise() before showSong()?

• What are the instance variables in the Song class?

• What roles do methods perform?

• Can methods invoke other methods?

• Where are the instance variables initialized?