Whats wrong with my Implementation

[Kelvin Okornoe]

Am working on this question from https://stepik.org/lesson/77968/step/5?unit=54819

This is the question

Given an interface named AccountService. The interface has two abstract methods:

findAccountByOwnerId(long id) returns Account found by owner id or null.
countAccountsWithBalanceGreaterThan(long balance) returns number of accounts with the balance greater than the passed value.
Also there are two another classes: Account (id, balance, owner) and User (id, firstName, lastName). See the provided code template.

You need to implement the AccountService interface and its two methods. Your implementation must be named AccountServiceImpl. 
It should have a constructor with one argument - an array of accounts. 
The implementation must keep the array inside. 
The first method should search an account by owner id in the array, the second one - count number of accounts by condition in the array.

An example of creating an instance:

Account[] accounts = ...
AccountService service = new AccountServiceImpl(accounts);
Do not make classes and the interface public. 

This is the code template provided.

interface AccountService {
  /**
   * It finds an account by owner id
   * @param id owner unique identifier
   * @return account or null
   */
  Account findAccountByOwnerId(long id);
  /**
   * It count the number of account with balance > the given value
   * @param value
   * @return the number of accounts
   */
  long countAccountsWithBalanceGreaterThan(long value);
}

// Declare and implement your AccountServiceImpl here

class Account {

  private long id;
  private long balance;
  private User owner;

  public Account(long id, long balance, User owner) {
    this.id = id;
    this.balance = balance;
    this.owner = owner;
  }

  public long getId() { return id; }

  public long getBalance() { return balance; }

  public User getOwner() { return owner; }
}

class User {

  private long id;
  private String firstName;
  private String lastName;

  public User(long id, String firstName, String lastName) {
    this.id = id;
    this.firstName = firstName;
    this.lastName = lastName;
  }

  public long getId() { return id; }

  public String getFirstName() { return firstName; }

  public String getLastName() { return lastName; }
}

This is my current implementation

interface AccountService {
  /**
   * It finds an account by owner id
   * @param id owner unique identifier
   * @return account or null
   */
  Account findAccountByOwnerId(long id);
  /**
   * It count the number of account with balance > the given value
   * @param value
   * @return the number of accounts
   */
  long countAccountsWithBalanceGreaterThan(long value);
}

// Declare and implement your AccountServiceImpl here
class AccountServiceImpl implements AccountService {
  Account[] account;
  long countAccount = 0L;

  AccountServiceImpl(Account[] accounts) {
    this.account = accounts;
  }

  @Override
  public Account findAccountByOwnerId(long id) {
    for (Account acc : account)
      if(acc.getId() == id)
    return acc;
  }


  @Override
  public long countAccountsWithBalanceGreaterThan(long value) {
    for (Account acc : account) {
      if (acc.getBalance() > value) {
        countAccount++;
      }
    }
    return countAccount;
  }

}
  class Account {

    private long id;
    private long balance;
    private User owner;

    public Account(long id, long balance, User owner) {
      this.id = id;
      this.balance = balance;
      this.owner = owner;
    }

    public long getId() {
      return id;
    }

    public long getBalance() {
      return balance;
    }

    public User getOwner() {
      return owner;
    }
  }

  class User {

    private long id;
    private String firstName;
    private String lastName;

    public User(long id, String firstName, String lastName) {
      this.id = id;
      this.firstName = firstName;
      this.lastName = lastName;
    }

    public long getId() {
      return id;
    }

    public String getFirstName() {
      return firstName;
    }

    public String getLastName() {
      return lastName;
    }
  }

 

But I am stacked with the method findAccountByOwnerId(), the problem is with returning the value from the method. I do not know what am doing wrong here. Line 30 gives me an error.
Any help will be appreciated.

[Tim Moores]

A method with a return value must in all cases return a value. Here, it may not, if there is no account with ID id. You may assume that there will always be such an account, but you need to convince the compiler that it will always have an Account object to return (or possibly return null otherwise).

    for (Account acc : account)
      if(acc.getId() == id)
    return acc;

Don't write a loop like this, without enclosing braces. My personal rule is that I *may* omit the braces if the for or if contains only a single line of code, but I rarely do. Probably rather sooner than later the time will come to add a second statement, at which point you need to remember to add braces anyway. Plus, it makes the code clearer to read for other people, or yourself, six months down the road.

[Campbell Ritchie]

Tim Moores wrote:. . . Don't write a loop like this, without enclosing braces. . . . .

Especially not if you indent the code incorrectly.