public/subjects/java/piscine/StarPlanet

StarPlanet

Instructions

Create a new class Planet in a file named Planet.java.

This class inherits CelestialObject.
It has one private property : centerStar of type Star.

There are two constructors :

• One with no parameters, which calls the superclass constructor with no parameters. In this case, the centerStar property is initialised with the default Star constructor.
• The other with many parameters :
  • name
  • x
  • y
  • z
  • centerStar which calls the superclass constructor with full parameters.

We add a getter and a setter for the centerStar property (getCenterStar and setCenterStar).

We override the hashCode and equals, using the centerStar property.

Finally, we override toString method. The returned String must have the following format : <name> circles around <centerStar.name> at the <distanceWithCenterStar> AU. The distanceWithCenterStar is computed with the help of distanceBetween method taking as parameter the planet and its center star.##

Usage

Here is a possible ExerciseRunner.java to test your function :

public class ExerciseRunner {

    public static void main(String[] args) {
        Planet earth = new Planet();
        Planet naboo = new Planet("Naboo", 17.4389, 8349.1, 8943.92, new Star("Betelgeuse", 128.23, -12.82, 32.328, 1289.3));

        System.out.println(naboo.toString());
        System.out.println(earth.toString());
        System.out.println(naboo.getCenterStar().toString());
    }
}

and its output :

$ javac *.java -d build
$ java -cp build ExerciseRunner
Naboo circles around Betelgeuse at the 12220.902 AU
Soleil circles around Soleil at the 0.000 AU
Betelgeuse shines at the 1289.300 magnitude
$