public class Person
{
    // instance variables - replace the example below with your own
    private String name;
    private int age;
    private String address;




    /**
     * Constructor for objects of class Person
     */
    public Person()
    {
       this.name = name;
       this.age = age;
       this.address = address;
    }



    //Set Methods:
    public void setName () {
            this.name = name;
    }


    public void setAge () {
            this.age = age;
    }


    public void setAddress () {
            this.address = address;
    }


    //Get Methods:
    public String getName () {
            return name;
    }

    public int getAge () {
            return age;
    }

    public String getAddress () {
            return address;
    }
}

public class Dog
{
    // instance variables - replace the example below with your own
    private String name;
    private int age;



    public Dog()
    {
       this.name = name;
       this.age = age;
    }


    //Set Methods:
    public void setName () {
        this.name = name;
    }

    public void setAge () {
        this.age = age;
    }

    //Get Methods:
    public String getName () {
        return name;
    }

    public int getAge () {
        return age;
    }


}

public class Main
{
   //Blank
}

public class Person
    {
    ArrayList<Dog> dogs=new ArrayList<Dog>(); //this will hold all the dogs that the Person has as pets

    public void giveDog(Dog dog){
       dogs.add(dog)
    }
    .....
    .....

public class Dog
    {
    Person owner;

    public void setOwner(Person owner){
       this.owner=owner;
    }
    .....
    .....

public class Person
   Set<Dog> dogs = new HashSet<Dog>();


   public void addDog(Dog dog){
      if(dogs.size()>20){
           throw new IllegalArgumentException("exceeded the limit: ");
      }
      dogs.add(dog);
   }
}

public class Dog
{
    Person person;

    public void setPerson(Person person){
        this.person=person;
    }
}

public class Person
{
    private Dog myDog;

    private String name;
    private int age;
    private String address;
    ...etc.

public class Dog
{
    private Person myOwner;

    private String name;
    private int age;

private Dog myDog;

private Dog[] dogArray = new Dog[20];
OR
private Collection<Dog> dogList = new ArrayList(20); //for example

Person person = new Person();
    Dog dog1 = new Dog();
    dog1.setAge(12);

    Dog dog2 = new Dog();
    dog2.setAge(34);

    person.addDog(dog1); //dog 1
    person.addDog(dog2); //dog 2
    person.listDogs(); //list of all dogs

public class Person {
 // instance variables - replace the example below with your own
    private String name;
    private int age;
    private String address;
    private ArrayList<Dog> dogs = new ArrayList<Dog>();



    /**
     * Constructor for objects of class Person
     */
    public Person()
    {
       this.name = name;
       this.age = age;
       this.address = address;
    }

    public void addDog(Dog dog) {
        this.dogs.add(dog);
    }

    public void listDogs() {
        for(Dog item : this.dogs) {
            System.out.println(item.getAge());
        }
    }



    //Set Methods:
    public void setName () {
            this.name = name;
    }


    public void setAge () {
            this.age = age;
    }


    public void setAddress () {
            this.address = address;
    }


    //Get Methods:
    public String getName () {
            return name;
    }

    public int getAge () {
            return age;
    }

    public String getAddress () {
            return address;
    }
}

public class Dog {

    // instance variables - replace the example below with your own
    private String name;
    private int age;



    public Dog()
    {
       this.name = name;
       this.age = age;
    }


    //Set Methods:
    public void setName () {
        this.name = name;
    }

    public void setAge (int age) {
        this.age = age;
    }

    //Get Methods:
    public String getName () {
        return name;
    }

    public int getAge () {
        return age;
    }


}