public/subjects/java/piscine/StarUtils

StarUtils

Instructions

Now, let's add some useful methods to our class.

First, toString method which returns a literal version of our class. The format is the following : <name> is positioned at (<x>, <y>, <z>). The printed double will have a precision of 3 decimals.

Then, equals(Object object) method which will return true if all properties of the object in parameter are equal to the current object.

As we have overriden equals method, we need to override hashCode method. This method returns an integer. If two objects are equal (using the equals method), then the results of their hashCode method should be equal.

Usage

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

public class ExerciseRunner {

    public static void main(String[] args) {
        CelestialObject celestialObject = new CelestialObject();
        CelestialObject earth = new CelestialObject("Terre", 1.0, 2.0, 2.0);
        CelestialObject earth1 = new CelestialObject("Terre", 1.0, 2.0, 2.0);

        System.out.println(earth.toString());
        System.out.println(earth.equals(earth1));
        System.out.println(earth.equals(celestialObject));

        System.out.println(earth.hashCode());
        System.out.println(celestialObject.hashCode());
    }
}

and its output :

$ javac *.java -d build
$ java -cp build ExerciseRunner
Terre is positioned at (1.000, 2.000, 2.000)
true
false
2129490293
-1811995559
$

Notions

Equals
HashCode
ToString