Vector.java

public class Vector {
    public final double x;
    public final double y;

    public Vector() {
        this(0, 0);
    }

    public Vector(double x) {
        this(x, 0);
    }

    public Vector(double x, double y) {
        this.x = x;
        this.y = y;
    }

    public Vector add(Vector v) {
        double newX = this.x + v.x;
        double newY = this.y + v.y;
        return new Vector(newX, newY);
    }

    public Vector substract(Vector v) {
        double newX = this.x - v.x;
        double newY = this.y - v.y;
        return new Vector(newX, newY);
    }

    public double dot(Vector v) {
        return this.x * v.x + this.y * v.y;
    }

    public static void main(String[] args) {
        Vector t1 = new Vector();
        boolean isNoParameterConstructorInitializing = t1.x == 0 && t1.y == 0;
        assert isNoParameterConstructorInitializing;

        Vector t2 = new Vector(1);
        boolean isOneParameterConstructorInitializing = t2.x == 1 && t2.y == 0;
        assert isOneParameterConstructorInitializing;

        Vector t3 = new Vector(2, 3);
        boolean isTwoParameterConstructorInitializing = t3.x == 2 && t3.y == 3;
        assert isTwoParameterConstructorInitializing;

        Vector t4 = t1.add(t2);
        boolean isAddWorking = (t4.x == (t1.x + t2.x)) && (t4.y == (t1.y + t2.y));
        assert isAddWorking;

        Vector t5 = t1.substract(t2);
        boolean isSubstractWorking = (t4.x == (t1.x - t2.x)) && (t4.y == (t1.y - t2.y));
        assert isSubstractWorking;

        double dotProd = t2.dot(t3);
        boolean isDotProductWorking = dotProd == t2.x * t3.x + t2.y * t3.y;
        assert isDotProductWorking;

    }
}