Hi all,

I am a newbie of Java and am working on my homework. I got an error
message "NullPointerException" after compilation. I know this means
values cannot be passed to array but it seems not my case because it
can generate a correct output on screen. The program terminate
abnormally after this error message. Could anyone help to point out
what I did wrong, thanks a lot.

et

Compilation Output :
------------------------------
Accounts of Amy
1234 : $1000.0
1122 : $5000.0
Exception in thread "main" java.lang.NullPointerException
       at Person.displayAccount(Person.java:29)
       at TestPerson.main(TestPerson.java:23)

Person Class
--------------------
public class Person {

   //attributes
   private String name;
   private Account[] account = new Account[10];

   //constructor
   public Person(String name, Account[] account){
      this.name = name;
      this.account = account;
      }

   //create getter for name
   public String getName(){
       return name;
       }

   //create setter for name
   public void setName(String setName){
       name = setName;
       }

   //create displayAccount method
   public void displayAccount(){
       System.out.println("Accounts of " + name);
       for(int i=0; i<account.length; i++){
       System.out.println(account[i].getNumber() +" : $"+
account[i].getBalance());
       }
   }

   //create lowBalanceAccounts method
   public String lowBalanceAccounts(double lowBalance){
       String msg = "No account's balance is lower than Low balance";
       for(int i=0; i<account.length; i++){
           if(account[i].getBalance() < lowBalance)
               return account[i].getNumber();
           }
        return msg;
       }

   //create highestBalanceAccount Method
   public String highestBalanceAccount(){
       double hBal = 0;
       String acNo = null;
       for(int i=0; i<account.length; i++){
           if(account[i].getBalance() > hBal){
               hBal = account[i].getBalance();
               acNo = account[i].getNumber();
           }
       }
       return acNo;
   }

}

TestPerson Class
--------------------------

//The class of TestPerson creates an environment
//for testing Person object

public class TestPerson {

   public static void main(String Arg[]) {

   //Attribute
   int accountCount = 0;
   Account[] account = new Account[10];

   //create account and person objects for Amy
   Account account1 = new Account("1234", 1000);
   Account account2 = new Account("1122", 5000);
   account[0] = account1;
   account[1] = account2;
   Person amy = new Person("Amy", account);

   //System.exit(-1);

   //call displayAccounts method
   amy.displayAccount();

   //call lowBalance accounts
   System.out.println("Low balance account(s) :
"+amy.lowBalanceAccounts(2000));

   //call highestBalanceAccount
   System.out.println("The highest account is :
"+amy.highestBalanceAccount());
   
   }
}