Initial commit for #1

src/main/java/_1/_1/Animal.java

@@ -0,0 +1,125 @@
+package _1._1;
+
+import java.util.*;
+import java.util.stream.Collectors;
+
+public class Animal {
+	private String name;
+	private Plant[] plantFoods; //null if empty
+	private Animal[] animalFoods; //null if empty
+
+	public Animal(String name) {
+		this.name = name;
+	}
+
+	/**
+	 * Gives the animal the ability to eat a new plant
+	 */
+	public void addFood(Plant food) {
+		if(this.plantFoods == null) {
+			this.plantFoods = new Plant[10];
+		}
+		for(int i = 0; i < this.plantFoods.length; i++) {
+			if(this.plantFoods[i] == null) {
+				this.plantFoods[i] = food;
+			}
+		}
+	}
+
+	/**
+	 * Gives the animal the ability to eat a new animal
+	 */
+	public void addFood(Animal food) {
+		if(this.animalFoods == null) {
+			this.animalFoods = new Animal[10];
+		}
+		for(int i = 0; i < this.animalFoods.length; i++) {
+			if(this.animalFoods[i] == null) {
+				this.animalFoods[i] = food;
+			}
+		}
+	}
+
+	//collects all non-null entries from an array in a set
+	private static <T> Set<T> nonNullEntries(T[] array) {
+		if(array == null) {
+			return new HashSet<>();
+		}
+		return Arrays.stream(array)
+				.filter(Objects::nonNull)
+				.collect(Collectors.toSet());
+	}
+
+	/**
+	 * Provides read-only access to the plants this animal eats.
+	 */
+	public Collection<Plant> getPlantFoods() {
+		return nonNullEntries(this.plantFoods);
+	}
+
+	/**
+	 * Provides read-only access to the animals this animal eats.
+	 */
+	public Collection<Animal> getAnimalFoods() {
+		return nonNullEntries(this.animalFoods);
+	}
+
+	/*
+	 * Es gibt keine setter für die Nahrung, weil ich dann keine Annahmen mehr
+	 * über die beiden Arrays machen könnte, ohne dem Anwender alle implementation details
+	 * zu verraten und mich darauf zu verlassen das sie eingehalten werden.
+	 *
+	 * Das ist zwar zu diesem Zeitpunkt kein Problem, würde es aber erschweren
+	 * neue Funktionen hinzuzufügen.
+	 *
+	 * Lieber würde ich eine andere Datenstruktur wie Listen oder Sets verwenden,
+	 * aber leider verbietet die Aufgabenstellung dies.
+	 */
+
+	/**
+	 * @return true if this animal can eat at least one plant.
+	 */
+	/*
+	 * Könnte private sein, aber ich habe mich dagegen entschieden weil ich diese Methoden
+	 * für ähnlich praktisch wie isCarnivore(), isOmnivore() und isHerbivore() halte.
+	*/
+	public boolean eatsPlants() {
+		return this.plantFoods != null;
+	}
+
+	/**
+	 * @return true if this animal can eat at least one animal.
+	 */
+	public boolean eatsAnimals() {
+		return this.animalFoods != null;
+	}
+
+	/**
+	 * @return true if this animal can only eat animals but no plants.
+	 */
+	public boolean isCarnivore() {
+		return this.eatsAnimals() && !this.eatsPlants();
+	}
+
+	/**
+	 * @return true if this animal can eat plants and animals
+	 */
+	public boolean isOmnivore() {
+		return this.eatsAnimals() && this.eatsPlants();
+	}
+
+	/**
+	 * @return true if this animal can only eat plants but no animals.
+	 */
+	public boolean isHerbivore() {
+		return !this.eatsAnimals() && this.eatsPlants();
+	}
+
+	public String getName() {
+		return this.name;
+	}
+
+	public void setName(String name) {
+		this.name = name;
+	}
+}

src/main/java/_1/_1/BioTest.java

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+package _1._1;
+
+public class BioTest {
+    public static void main(String[] args) {
+        Plant grass = new Plant("Grass", "is green");
+        Plant berry = new Plant("Berry", "is red");
+        Animal zebra = new Animal("Zebra");
+        zebra.addFood(grass);
+        Animal lion = new Animal("Lion");
+        lion.addFood(zebra);
+        Animal bear = new Animal("Bear");
+        bear.addFood(berry);
+        Animal fish = new Animal("Fish");
+        bear.addFood(fish);
+
+        System.out.println(getFoodClassDescription(zebra));
+        System.out.println(getFoodClassDescription(lion));
+        System.out.println(getFoodClassDescription(bear));
+    }
+
+    private static String getFoodClassDescription(Animal animal) {
+        if(animal.isHerbivore()) {
+            return animal.getName() + " is a herbivore";
+        } else if(animal.isCarnivore()) {
+            return animal.getName() + " is a carnivore";
+        } else if(animal.isOmnivore()) {
+            return animal.getName() + " is an omnivore";
+        } else {
+            return animal.getName() + " is water fasting";
+        }
+    }
+}

src/main/java/_1/_1/Plant.java

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+package _1._1;
+
+public class Plant {
+    private String name;
+    private String description;
+
+    public Plant(String name, String description) {
+        this.name = name;
+        this.description = description;
+    }
+
+    public String getName() {
+        return this.name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getDescription() {
+        return this.description;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+}