Attempt at ZooProject failed code

Animal.java

+import java.util.ArrayList;
+
+public class Animal {
+
+    static String name;
+    static String diet;
+    static String food;
+    static String habitat;
+    static String type;
+
+    public Animal(String name, String type, String diet, String food, String habitat) {
+
+        Animal.name = name;
+        Animal.type = type;
+        Animal.diet = diet;
+        Animal.food = food;
+        Animal.habitat = habitat;
+
+    }
+
+    public String display() {
+
+        return "Name: " + name + "\n" + "Type: " + type + "\n" + "Diet: " + diet + "\n"
+                + "Food: " + food + "\n" + "Habitat: " + habitat;
+    }
+
+    public String group1() {
+
+        ArrayList<String> mammals = new ArrayList<String>();
+        ArrayList<String> birds = new ArrayList<String>();
+        ArrayList<String> fish = new ArrayList<String>();
+        ArrayList<String> reptiles = new ArrayList<String>();
+
+        if (type.contains("Mammal")) {
+
+            mammals.add(name);
+            System.out.println("Mammals list: " + mammals);
+
+        } else {
+            System.out.println();
+        }
+
+        if (type.contains("Bird")) {
+
+            birds.add(name);
+            System.out.println("Birds list: " + birds);
+
+        } else {
+            System.out.println();
+        }
+
+        if (type.contains("Fish")) {
+
+            fish.add(name);
+            System.out.println("Fish list: " + fish);
+
+        } else {
+            System.out.println();
+        }
+
+        if (type.contains("Reptile")) {
+
+            reptiles.add(name);
+            System.out.println("Reptile list: " + reptiles);
+
+        } else {
+            System.out.println();
+        }
+        return "";
+
+    }
+
+    public String group2() {
+
+        ArrayList<String> carnivores = new ArrayList<String>();
+        ArrayList<String> herbivores = new ArrayList<String>();
+        ArrayList<String> omnivores = new ArrayList<String>();
+
+        if (diet.contains("Carnivore")) {
+
+            carnivores.add(name);
+            System.out.println("Carnivore list: " + carnivores);
+
+        } else {
+            System.out.println();
+        }
+
+        if (diet.contains("Herbivore")) {
+
+            herbivores.add(name);
+            System.out.println("Herbivore list: " + herbivores);
+
+        } else {
+            System.out.println();
+        }
+
+        if (diet.contains("Omnivore")) {
+
+            omnivores.add(name);
+            System.out.println("Omnivore list: " + omnivores);
+
+        } else {
+            System.out.println();
+        }
+        return "";
+    }
+
+    public String group3() {
+
+        ArrayList<String> jungle = new ArrayList<String>();
+        ArrayList<String> desert = new ArrayList<String>();
+        ArrayList<String> arctic = new ArrayList<String>();
+
+        if (habitat.contains("Jungle")) {
+
+            jungle.add(name);
+            System.out.println("Animals in jungle habitat: " + jungle);
+
+        } else {
+            System.out.println();
+        }
+
+        if (habitat.contains("Arctic")) {
+
+            arctic.add(name);
+            System.out.println("Animals in arctic habitat: " + arctic);
+
+        } else {
+            System.out.println();
+        }
+
+        if (habitat.contains("Desert")) {
+
+            desert.add(name);
+            System.out.println("Animals in desert habitat: " + desert);
+
+        } else {
+            System.out.println();
+        }
+        return "";
+
+    }
+
+    public static void main(String[] args) {
+
+        Animal Animal1 = new Animal("Tiger", "Mammal", "Carnivore", "Meat", "Jungle");
+        Animal Animal2 = new Animal("Bear", "Mammal", "Omnivore", "Meat/plants", "Forest");
+        Animal Animal3 = new Animal("Shark","Fish", "Carnivore", "Meat", "Aquatic");
+        Animal Animal4 = new Animal("Iguana", "Reptile", "Herbivore", "Plants", "Forest");
+        Animal Animal5 = new Animal("Cheetah", "Mammal", "Carnivore", "Meat", "Desert");
+
+
+        System.out.println(Animal1.group1());
+        System.out.println(Animal2.group1());
+        System.out.println(Animal3.group1());
+        System.out.println(Animal4.group1());
+        System.out.println(Animal5.group1());
+
+    }
+
+}