I would like some help in completing this exercise. Thank You

import java.util.ArrayList; import java.util.Arrays;

public class ContactManager { // declare the contact ArrayList as an instance variable here.

/** * Initialize an empty ContactManager. */ public ContactManager() { throw new UnsupportedOperationException("Remove this line and replace with your implementation."); }

/** * Initialize a ContactManager which contains all the Contacts in the given * array. */ public ContactManager(Contact[] contacts) { throw new UnsupportedOperationException("Remove this line and replace with your implementation."); }

/** * Given 4 String parameters, add a contact to the contacts list. If first name * or last name is null or an empty string, then do not add a contact but return * false. * * Otherwise, create a new contact, and add the phone number to the new contact. * If the phone number is in a valid format, add the contact to the list and * return true. You may not rewrite the validity check method but can simply * reuse the Contact class code written for L5. * * We allow adding duplicate contacts. Note that there is no limit to how many * times this method can be called. * * @param fName * @param lName * @param mName * @param phoneNumber * @return a boolean value. See the description above */ public boolean addContact(String fName, String lName, String mName, String phoneNumber) { throw new UnsupportedOperationException("Remove this line and replace with your implementation."); }

/** * Remove the Contact with Name n from your List. Make no changes if it doesn't * exist. * * @param n */ public void removeContact(Name n) { throw new UnsupportedOperationException("Remove this line and replace with your implementation."); }

/** * Return whether the Contact List contains a Contact with Name n or not. Hint: * A 1-line solution exists. */ public boolean contains(Name n) { throw new UnsupportedOperationException("Remove this line and replace with your implementation."); }

/** * Return the number of contacts (int) Hint: A 1-line solution exists. */ public int countContacts() { throw new UnsupportedOperationException("Remove this line and replace with your implementation."); }

/** * Return a toString of the contacts. The toString() method should call the * Contact toString() method and add a new line after every Contact, EXCEPT the * last. Example Output with 2 contacts: * * Name: __________ (Phone Number: ___-___-____) Name: __________ (Phone Number: * ___-___-____) */ public String toString() { throw new UnsupportedOperationException("Remove this line and replace with your implementation."); }

}