set Challenge

(출처 : Udemy Programming masterclass for software developers)

-Main

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package com.timbuchalka;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

public class Main {
    private static Map<String, HeavenlyBody> solarSystem = new HashMap<>();
    private static Set<HeavenlyBody> planets = new HashSet<>();

    public static void main(String[] args) {
        HeavenlyBody temp = new HeavenlyBody("Mercury", 88);
        solarSystem.put(temp.getName(), temp);
        planets.add(temp);

        temp = new HeavenlyBody("Venus", 225);
        solarSystem.put(temp.getName(), temp);
        planets.add(temp);

        temp = new HeavenlyBody("Earth", 365);
        solarSystem.put(temp.getName(), temp);
        planets.add(temp);

        HeavenlyBody tempMoon = new HeavenlyBody("Moon", 27);
        solarSystem.put(tempMoon.getName(), tempMoon);
        temp.addMoon(tempMoon);

        temp = new HeavenlyBody("Mars", 687);
        solarSystem.put(temp.getName(), temp);
        planets.add(temp);

        tempMoon = new HeavenlyBody("Deimos", 1.3);
        solarSystem.put(tempMoon.getName(), tempMoon);
        temp.addMoon(tempMoon); // temp is still Mars

        tempMoon = new HeavenlyBody("Phobos", 0.3);
        solarSystem.put(tempMoon.getName(), tempMoon);
        temp.addMoon(tempMoon); // temp is still Mars

        temp = new HeavenlyBody("Jupiter", 4332);
        solarSystem.put(temp.getName(), temp);
        planets.add(temp);

        tempMoon = new HeavenlyBody("Io", 1.8);
        solarSystem.put(tempMoon.getName(), tempMoon);
        temp.addMoon(tempMoon); // temp is still Jupiter

        tempMoon = new HeavenlyBody("Europa", 3.5);
        solarSystem.put(tempMoon.getName(), tempMoon);
        temp.addMoon(tempMoon); // temp is still Jupiter

        tempMoon = new HeavenlyBody("Ganymede", 7.1);
        solarSystem.put(tempMoon.getName(), tempMoon);
        temp.addMoon(tempMoon); // temp is still Jupiter

        tempMoon = new HeavenlyBody("Callisto", 16.7);
        solarSystem.put(tempMoon.getName(), tempMoon);
        temp.addMoon(tempMoon); // temp is still Jupiter

        temp = new HeavenlyBody("Saturn", 10759);
        solarSystem.put(temp.getName(), temp);
        planets.add(temp);

        temp = new HeavenlyBody("Uranus", 30660);
        solarSystem.put(temp.getName(), temp);
        planets.add(temp);

        temp = new HeavenlyBody("Neptune", 165);
        solarSystem.put(temp.getName(), temp);
        planets.add(temp);

        temp = new HeavenlyBody("Pluto", 248);
        solarSystem.put(temp.getName(), temp);
        planets.add(temp);

        System.out.println("Planets");
        for(HeavenlyBody planet : planets) {
            System.out.println("\t" + planet.getName());
        }

        HeavenlyBody body = solarSystem.get("Mars");
        System.out.println("Moons of " + body.getName());
        for(HeavenlyBody jupiterMoon: body.getSatellites()) {
            System.out.println("\t" + jupiterMoon.getName());
        }

        Set<HeavenlyBody> moons = new HashSet<>();
        for(HeavenlyBody planet : planets) {
            moons.addAll(planet.getSatellites());
        }

        System.out.println("All Moons");
        for(HeavenlyBody moon : moons) {
            System.out.println("\t" + moon.getName());
        }

        HeavenlyBody pluto = new HeavenlyBody("Pluto", 842);
        planets.add(pluto);

        for(HeavenlyBody planet : planets) {
            System.out.println(planet.getName() + ": " + planet.getOrbitalPeriod());
        }

        Object o = new Object();
        o.equals(o);
        "pluto".equals("");
    }
}

  • HeavenlyBody
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    package com.chung;

    import java.util.HashSet;
    import java.util.Set;


    public final class HeavenlyBody {
        private final String name;
        private final double orbitalPeriod;
        private final Set<HeavenlyBody> satellites;

        public HeavenlyBody(String name, double orbitalPeriod) {
            this.name = name;
            this.orbitalPeriod = orbitalPeriod;
            this.satellites = new HashSet<>();

        }

        public String getName() {
            return name;
        }

        public double getOrbitalPeriod() {
            return orbitalPeriod;
        }

        public boolean addMoon(HeavenlyBody moon) {

            return this.satellites.add(moon);
        }

        public Set<HeavenlyBody> getSatellites() {
            return new HashSet<>(this.satellites);
        }


        @Override
        public boolean equals(Object obj) {
            if(this == obj) {
                return true;
            }

            System.out.println("obj.getClass() is " + obj.getClass());
            System.out.println("this.getClass() is " + this.getClass());
            if ((obj == null) || (obj.getClass() != this.getClass())) {
                return false;
            }

            String objName = ((HeavenlyBody) obj).getName();
            return this.name.equals(objName);
        }

        @Override
        public int hashCode() {
            System.out.println("hashcode called");
            return this.name.hashCode() + 57;
        }
    }