Anatomy of Java

• Basic Java Class
• Methods
• Class Attributes with Objects
• Constructors
• Getters and Setters
• Dessert Example

Basic Java Class

// Main Class. Name of class needs to be the same as filename
public class Hello {

    // The main method. First thing program does is find this method and run it
    public static void main(String[] args) {
        System.out.println("Hello");
    }
}

Hello.main(null); 
// Calls main method with passing nothing for parameter

Hello

Methods

public class Sports {

    // Method called sportIntro. Similar to functions in python
    static void sportIntro() {
        System.out.println("I love sports");
    }

    public static void main(String[] args) {
        // calls method/function
        sportIntro();
    }
}

Sports.main(null);

I love sports

Class Attributes with Objects

public class Sports {

    // attributes of the class Sports
    String name;
    double population;

    public static void main(String[] args) {
        // Creating new object called basketball
        Sports basketball = new Sports();
        // setting attributes for the object basketball
        basketball.name = "Basketball";
        basketball.population = 24.23; // in millions

        System.out.println("For the game of " + basketball.name + ", " + basketball.population + " million people play!");

    }
}

Sports.main(null);

For the game of Basketball, 24.23 million people play!

Constructors

public class Sports {
    String name;

    // constructor for the class Sports. Needs to be same name as class
    public Sports(String title) {
        name = title;
    }

    public static void main(String[] args) {
        Sports basketball = new Sports("Basketball is the best sport");
        System.out.println(basketball.name);
    }
}

Sports.main(null);

Basketball is the best sport

Getters and Setters

• Private Variables

public class Sports {
    // can only be changed with a setter
    private String title;

    // returns private variable information
    public String getTitle() {
        return title;
    }

    // only thing that can change the private variable title
    public void setTitle(String title) {
        this.title = title;
    }
}

public class Main {
    public static void main(String[] args) {
        Sports basketball = new Sports();
        basketball.setTitle("basketball");

        System.out.println(basketball.getTitle());
    }
}

Main.main(null);

basketball

Dessert Example

public class Desserts {

    // setting class attributes that can only be accessed with setter/getter
    private String name;
    private int price;

    // intiailize variables in constructor
    public Desserts() {
        name = "dessert";
        price = 5;
    }
    // setter method
    public void setDesc(String name, int price) {
        System.out.println("In Setter");
        this.name = name;
        this.price = price;
    }
    // getter method
    public String getDesc() {
        return "The name of the dessert is " + this.name + " and the price is $" + this.price;
    }

    public static void main(String[] args) {
        Desserts Dessert1 = new Desserts();

        Dessert1.setDesc("Cake", 10);

        System.out.println(Dessert1.getDesc());
    }
}

Desserts.main(null);

In Setter
The name of the dessert is Cake and the price is $10