[Java] OOP

Syntax

Class

public class Dog {
    public String name;
    public int weight;
    private String gender; // Read Only, can only accessed within the class

    // Constructor function
    // public Dog(String name, int weight, String gender) {
    //     this.name = name;
    //     this.weight = weight;
    //     this.gender = gender;
    // }

    // Or use this
    public Dog(String nm, int wt, String gen) {
        name = nm;
        weight = wt;
        gender = gen;
    }

    public void getGender() {
        System.out.println(gender);
    }

    public void Bark() {
        System.out.println("WOOF");
    }

    public void Run() {
        System.out.println("RUN");
    }
}

public class Main {
    public static void main(String[] args) {
        Dog myDog = new Dog("Xiaoguai", 12, "female");
        Dog yourDog = new Dog("Test", 10, "female");

        System.out.println(myDog.name);

        myDog.Bark();

    }
}

Getters and Setters

public class Ball {
    // ...
    public String getColor() {
        return color;
    }

    public String getName() {
        return name;
    }

    // Setter
    public void setColor(String color) {
        this.color = color;
    }

    public void setName(String name) {
        this.name = name;
    }
}

Overloading

Overloading allows us to have as many constructors(with different signatures) as we want in a class.

public class Ball {
    public Ball() {} // Constructor 1
    public Ball(String nm, int wt, String gen) { // Constructor 2
        name = nm;
        weight = wt;
        gender = gen;
    }
    public Ball(String nm) {
        name = nm;
    }
}

public class Main {
    public static void main(String[] args) {
        Ball ball = new Ball();
        Ball myBall = new Ball("name", 12, "female");
        Ball yourBall = new Ball("yourName");
    }
}

Inheritance

public class Basketball extends Ball {
    public boolean isNBA;
    public int capacity;

    public int getCapacity() {
        return capacity;
    }

    // Override
    public void setName(String newName) {
        name = newName + "new";
    }
}