public class Main {

    public static void main(String[] args) {

	Mobile phone = new Mobile("xxx");
	phone.addContact("Jan Pawel", 2);

    }
}

import java.util.ArrayList;

public class Mobile {
    private String name;
    private ArrayList <Contact> contactList;

    public void addContact(String name, int number){
        contactList.add(new Contact(name,number));
    }

    public void printContactList(){
        for(int i=0;i<contactList.size();i++){
            System.out.println(contactList.get(i));
        }
    }

    //public int findContact(String name, int number){
    //}

    public Mobile(String name) {
        this.name = name;
        this.contactList = new ArrayList<Contact>();
    }
}

public class Contact {
    private String name;
    private int number;

    public Contact(String name, int number) {
        this.name = name;
        this.number = number;
    }

    public String getName() {
        return name;
    }

    public int getNumber() {
        return number;
    }

    @Override
    public String toString() {
        return "Contact{" +
                "name='" + name + '\'' +
                ", number=" + number +
                '}';
    }
}