encapsulation-in-java.md

Encapsulation in Java ☕

Today we are going to learn about encapsulation using Java!

OK! Let's write a vector class...

public class Vector2 {
    public float x;
    public float y;
}

Hang on... public fields are Bad Practice... what if they were to change in the future? We should be designing to an interface.

public interface Vector2 {
    float getX();
    float getY();
}

Better make those fields private!

public final class BasicVector2 implements Vector2 {
    private float x;
    private float y;
    
    public float getX() {
        return x;
    }
    
    public float getY() {
        return y;
    }
    
    public BasicVector2(float x, float y) {
        this.x = x;
        this.y = y;
    }
}

Hmmm... but we still need to be able to modify the vector!

Let's extend the interface...

public interface Vector2 {
    float getX();
    float getY();
    
    Vector2 setX(float x);
    Vector2 setY(float y);
}

... and the implementation.

public final class BasicVector2 implements Vector2 {
    private float x;
    private float y;
    
    public float getX() {
        return x;
    }
    
    public float getY() {
        return y;
    }
    
    public Vector2 setX(float x) {
        this.x = x;
        return this;
    }
    
    public Vector2 setY(float y) {
        this.y = y;
        return this;
    }
    
    public BasicVector2(float x, float y) {
        this.x = x;
        this.y = y;
    }
}

Isn't that so much better?

Now our data is encapsulated behind getters and setters!