Arraylist Object not finding method

Question

I am creating an arraylist of objects and trying to print them out. However, when I go to print it is not finding the method.

Researched arraylist Objects and copied some other code. I just can not seem to find the problem with my code.

public class Main{

   public static void main(String[] args){

  List<PhoneBook> users = new ArrayList<>();

  users.add(new PhoneBook("Paul", 4129991));
  users.add(new PhoneBook("Kelly", 5702135));

  for(int i = 0; i<users.size(); i++){
     System.out.println("PhoneBook " + PhoneBook.getName());
      }
   }
}




class PhoneBook{

  private String name; 
  private int phoneNumber;

public PhoneBook(String name, int phoneNumber){
   this.name = name;
   this.phoneNumber = phoneNumber;
}


   public String getName(){
     return name;
 }

 public int getPhoneNumber(){
   return phoneNumber;
 }

 public void setName(String name){
    this.name = name;
 }

 public void setPhoneNumber(int phoneNumber){
    this.phoneNumber = phoneNumber;
 }



}

Change PhoneBook.getName() to users.get(i).getName(). There is no static method getName() on PhoneBook, and you can also look at it this way: you're looping over a list of multiple users, but you're not in any way telling the compiler which user from the list you want to get the name for. That can't be right. — Erwin Bolwidt
– Erwin Bolwidt, Commented Oct 25, 2019 at 1:38

MarsAtomic · Accepted Answer · 2019-10-25 01:45:04Z

2

You're running into a problem because your users data structure is an ArrayList of PhoneBook objects, which means you should be attempting to manipulate elements within the ArrayList as opposed to manipulating a PhoneBook object which does not exist.

Change your existing code from:

for(int i = 0; i<users.size(); i++){
    System.out.println("PhoneBook " + PhoneBook.getName());
}

to:

for(int i = 0; i<users.size(); i++){
    System.out.println("PhoneBook " + users.get(i).getName());
}

Your code should be iterating through each element of the ArrayList by index (your i variable) and getting the name from each item within that ArrayList. PhoneBook is the name of a class, but does not refer to the elements of your data structure. Although those elements are instances of PhoneBook, invoking the class name doesn't refer to anything in particular, which is why the compiler complains.

edited Oct 25, 2019 at 1:45

answered Oct 25, 2019 at 1:38

MarsAtomic

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1 Comment

Pshemo Over a year ago

"users(i) gives a compile error" to avoid such problems use for-each like for (PhoneBook user : users){ ... user.getName(); ...}. Also that list probably shouldn't be called users but phoneBooks or maybe even PhoneBook shouldn't be called that way but rather PhoneBookEntry since it doesn't contain like standard phone book information about many people but it is entry about single person.

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