Programming in Java

Programming in Java Transitioning from Alice

Becomes not myFirstMethod but …. public static void main (String[] arg) { // code for testing classes goes here }

Your project and classes are similar

Both functions and methods are referred to as methods in Java

void methods are methods which do not return values

Methods with “return types” are often referred to as functions – just as in Alice, they can return numbers (called int or doubles), booleans, Strings, or Objects

Properties in Java are referred to as private instance variables

Simple Programs • Very simple program to print a name • Simple program to test a separate class and instantiated objects

Output from Play

Java from Eclipse main method

Running it Output

Bunny and UseBunny • Create a Bunny class • Properties : color and age • Modifier methods to change those properties • Accessor methods to return those properties • Special method of reach class used to create the instances – called constructor

class Bunny { //In Java need a constructor for every new class public Bunny() //set default properties { age = 0; color = "white"; } //private instance variables (like properties) int age; String color; Constructor and Instance Variables

Accessor Methods -- usually functions //accessor methods public String giveColorInfo() { return color; } public int giveAgeInfo() { return age; }

Modifier Methods // modifier methods – change properties public void setColor (String newColor) { color = newColor; } public void setAge (int newAge) { age = newAge; } }

UseBunny.java Revisited class UseBunny{ public static void main(String[] arg) { Bunny b = new Bunny(); //like add Object Bunny b1 = new Bunny(); b.setAge(6); b1.setColor("green"); System.out.println("The first bunny is :"); System.out.println(b.giveAgeInfo() + " and is " + b.giveColorInfo()); System.out.println("The second bunny is :"); System.out.println(b1.giveAgeInfo() + " and is " + b1.giveColorInfo()); } }

Java Assignment • Java Assignment 1 – • Part 1:Make the Lab1 project and run the FirstOne Java program • Part 2: Make the Lab1PtII project and get the UseBunny and Bunny to work

Programming in Java