Question

+1 change your code so that the animals array will have enough space for a 100 animals. (No need to add a 100 animals in the Farm's constructor - see the next two points) +4] Add a method boolean add (Animal anim) that adds an animal to the next empty spot in the animals array. For example, when you first create animals, it will have a 100 empty spots (i.e. all null). The code below adds a new chicken at index 0 and a cow at index 1. The remaining spots will remain empty (i.e. equal to null). myFarm.add (new Chicken ()) myFarm.add (new Cow ()); The add method should return true when the given animal is added successfully, and falsee when the farm is full (i.e. no empty spots in animals array) +1] modify the Farm's constructor to use the above add method in order to add a chicken, a cow, and two llamas. The animals array should now have exactly 4 animals and 96 empty spots. [+3] modify the getAnimals method so that it returns an array with existing animals only (i.e. don't return the full animals array if it has empty spots). For example, if you have only4 animals in your farm, getAnimals will return a new array of the size 4 with these 4 animals. +4] Add a method void animSort () that sorts the animals in the animals array based on their energy. You must use the Arrays.sort method in your implementation. For example, suppose that animals[Cowl, Chickenl, Llamal, null, null, ..., null] and assume that the order based on the energy is Llamal < Chickenl < Cow1. Then, animSort would change animals to: animals = [Llama 1 , Chicken!, Cowl, null, null, , null] +4] Implement any changes outside the Farmclass in order for animSort () to work properly.

help with java OOP, here is the started code:

package P2;
public class Farm {
   private double availableFood;
   private Animal[] animals;
   public Farm() {
       setAvailableFood(1000);
       animals = new Animal[4];
       animals[0] = new Chicken();
       animals[1] = new Cow();
       animals[2] = new Llama();
       animals[3] = new Llama();
   }
   public void makeNoise(){           // all animals make their sound (Moo, Cluck, etc)
       for(Animal animal: animals)
           animal.sound();
   }
   public void feedAnimals(){            // restore energy of all animals and deduct amount eaten from availableFood
       for(Animal animal : animals)
           if(availableFood >= Math.min(animal.getMealAmount(), (100-animal.getEnergy())))
           // no penalty if student uses: if(availableFood >= animal.getMealAmount())
               availableFood -= animal.eat();
           else
               System.out.println("Not enough food for your animals! You need to collect more food items.");
   }
   public double getAvailableFood() {
       return availableFood;
   }
   public void setAvailableFood(double availableFood) {
       if(availableFood>=0 && availableFood<=1000)
           this.availableFood = availableFood;
   }
   public Animal[] getAnimals() {
       return animals;
   }  
}

public class Animal {
   private String name;
   private double energy, mealAmount, x, y, speedX=1, speedY=1;
   private boolean alive;  
   public Animal() {
       setEnergy(100);
   }
   public void speak(String msg){
       if (isAlive()) System.out.println(getName() + " says: " + msg);
   }
   public double eat(){
       if (isAlive()) {
           //get amount needed and round to 2 decimals
           double amount = Math.round((100-getEnergy())*100)/100.0;
           if (amount >= mealAmount) {
               System.out.println(getName() + " ate " + mealAmount + " units");
               setEnergy(getEnergy() + mealAmount);
               return mealAmount;
           } else if (amount > 0) {
               System.out.println(getName() + " ate " + amount + " units. Now it is full!");
               setEnergy(100);
               return amount;
           } else {
               System.out.println(getName() + " didn't eat. It is full!");
               return 0;
           }
       } else {
           System.out.println(getName() + " is dead!");
           return 0;
       }
   }
   public void move() {
       if(isAlive()){
           x += speedX;
           y += speedY;
           setEnergy(getEnergy() - 0.1);
       }else
           System.out.println(getName() + "can't move. It is dead!");
   }
   public void sound(){if(isAlive()) System.out.println("Unknown sound!");}
   //setters, getters, toString
   public String getName() {
       return name;
   }
   public double getEnergy() {
       return energy;
   }
   public void setName(String name) {
       this.name = name;
   }
   public void setEnergy(double energy) {
       if(energy>0 && energy <=100)
           this.energy = energy;
       if(this.energy <= 17 )
           System.out.println(getName() + " says: I'm STARVING");
       else if(this.energy <= 50)
           System.out.println(getName() + " says: I'm hungry");
       this.alive = (energy > 0);   
   }
   public double getMealAmount() {
       return mealAmount;
   }
   public void setMealAmount(double mealAmount) {
       if(mealAmount>0 && mealAmount<100) this.mealAmount = mealAmount;
   }
   public double getX() {
       return x;
   }
   public void setX(double x) {
       this.x = x;
   }
   public double getY() {
       return y;
   }
   public void setY(double y) {
       this.y = y;
   }
   public double getSpeedX() {
       return speedX;
   }
   public void setSpeedX(double speedX) {
       this.speedX = speedX;
   }
   public double getSpeedY() {
       return speedY;
   }
   public void setSpeedY(double speedY) {
       this.speedY = speedY;
   }
   public boolean isAlive() {
       return alive;
   }
   public String toString(){
       //return String.format("Alive:%b Name:%-10sEnergy:%-7.1fLocation:(%-2.1f,%-2.1f)", isAlive(), name, energy,x,y);
       return String.format("%-8s: %-5s at (%-2.1f,%-2.1f) Energy=%-7.1f", name, isAlive()?"alive":"dead",x,y,energy);
   }  
}

thanks for your help!!

Answer 1

Thanks for posting the question, here are the first 4 changes requested in the question. I am only sharing the changes that i have updated/modified remaining methods you need to keep it as it is

______________________________________________________________________________________________

import java.util.Arrays;
import java.util.Comparator;

public class Farm {
    private double availableFood;
    private Animal[] animals;
    private int animalCount; // we need to add this variable to track the # of animals we have in the //array

    public Farm() {
        setAvailableFood(1000);
        animals = new Animal[100];
        animalCount=0;
//        animals[0] = new Chicken();
//        animals[1] = new Cow();
//        animals[2] = new Llama();
//        animals[3] = new Llama();
        add(new Chicken());
        add(new Cow());
        add(new Llama());
        add(new Llama());

    }

    public void animSort(){

        Arrays.sort(animals, new Comparator<Animal>() {
            @Override
            public int compare(Animal o1, Animal o2) {
                return (int) (o1.getEnergy()-o2.getEnergy());
            }
        });
    }

    public Animal[] getAnimals() {
        Animal[] cattles = new Animal[animalCount];
        for(int index=0;index<animalCount;index++){
            cattles[index]=animals[index];
        }
        return cattles;
    }


    public boolean add(Animal anim){

        if(animalCount<100){
            animals[animalCount]=anim;
            animalCount++;
            return true;
        }else{
            return false;
        }
    }

}