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60 lines
2.4 KiB
60 lines
2.4 KiB
1 year ago
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## StarMass
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### Instructions
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For this last exercise, let's compute the mass of all objects in a galaxy, according their type.
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Firstly, let's add a mass property (it will be an integer) to all objects. I let you guess in which class to put it ;)
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You need to add the getter and setter for this property too. You will need to add a mass argument to all the constructors.
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In the `Galaxy` class, we will add a new method `computeMassRepartition` which returns a Map. This map will have for key the Strings `Star`, `Planet` or `Other`. The values will be the sum of the mass of the object by their type.
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### Usage
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Here is a possible ExerciseRunner.java to test your function :
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```java
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public class ExerciseRunner {
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public static void main(String[] args) {
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Galaxy galaxy = new Galaxy();
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CelestialObject charron = new CelestialObject("Charron", -123.12, 392.238, 32.31, 157);
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CelestialObject lune = new CelestialObject("Lune", 3928.32, 327.239, -12.92, 3987);
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Star betelgeuse = new Star("Betelgeuse", 128.23, -12.82, 32.328, 1289.3, 538595);
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Star altair = new Star("Betelgeuse", 43894.34, -324.43, 9438.23, 123.54, 137273);
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Star bellatrix = new Star("Bellatrix", 584.34, 2103.32, -102.43, 413.2, 5483724);
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Planet naboo = new Planet("Naboo", 17.4389, 8349.1, 8943.92, betelgeuse, 32454);
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Planet tatooine = new Planet("Tatooine", 17.4389, 8349.1, 8943.92, betelgeuse, 2345);
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Planet mercure = new Planet("Mercure", 17.4389, 8349.1, 8943.92, altair, 19438);
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Planet venus = new Planet("Venus", 17.4389, 8349.1, 8943.92, altair, 9283);
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Planet mars = new Planet("Mars", 17.4389, 8349.1, 8943.92, altair, 2183);
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galaxy.addCelestialObject(lune);
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galaxy.addCelestialObject(charron);
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galaxy.addCelestialObject(mars);
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galaxy.addCelestialObject(mercure);
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galaxy.addCelestialObject(tatooine);
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galaxy.addCelestialObject(altair);
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galaxy.addCelestialObject(venus);
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galaxy.addCelestialObject(betelgeuse);
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galaxy.addCelestialObject(naboo);
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galaxy.addCelestialObject(bellatrix);
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System.out.println(galaxy.computeMassRepartition().toString());
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}
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}
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```
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and its output :
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```shell
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$ javac *.java -d build
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$ java -cp build ExerciseRunner
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{Star=6159592, Planet=65703, Other=4144}
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$
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```
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### Notions
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[InstanceOf](https://www.baeldung.com/java-instanceof)
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