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 classProperties : 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
Constructor and Instance Variables
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;
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 Revisitedclass 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
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