Vector3D with comments

package classes;
import classes.Point3D;

public class Vector3D {
    double x, y, z; // поля

    public Vector3D(double x, double y, double z){ //конструктор по координатам
        this.x = x;
        this.y = y;
        this.z = z;
    }

    public Vector3D(){ // конструктор по нулям
        this.x = 0;
        this.y = 0;
        this.z = 0;
    }

    public Vector3D(Point3D point1, Point3D point2){ // конструктор по двум точкам
        this.x = point2.x - point1.x;
        this.y = point2.y - point1.y;
        this.z = point2.z - point1.z;
    }

    public double Length(){
        return Math.sqrt(this.x*this.x + this.y*this.y + this.z*this.z);
    } // длина вектора

    @Override
    public boolean equals(Object o) { // снова сгенерировал проверку на равенство
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Vector3D vector3D = (Vector3D) o;

        if (Double.compare(vector3D.x, x) != 0) return false;
        if (Double.compare(vector3D.y, y) != 0) return false;
        return Double.compare(vector3D.z, z) == 0;
    }

    public String toString() { // возвращает координаты в формате строки
        return this.x +", " + this.y + ", " + this.z;
    }

    //проверки

    public static void main(String args[]){
        Point3D point_first = new Point3D(1, 1, 1);
        Point3D point_second = new Point3D(2, 2, 2);

        Vector3D vec1 = new Vector3D(1, 2, 3);
        Vector3D vec2 = new Vector3D(1, 2, 3);
        Vector3D vec3 = new Vector3D();

        if(vec1 == vec3) {System.out.println("Вектора равны");}
        else {System.out.println("Вектора не равны");}

        if(vec3 == vec3) {System.out.println("Вектор равен себе");}
        else {System.out.println("Вектор не равен себе");}

        if(vec1.equals(vec2)) {System.out.println("Вектора равны");}
        else {System.out.println("Вектора не равны");}

        System.out.println("Длина вектора = " +vec1.Length());
    }

}