CODEWITHSUNDEEP
java-menullpointerexception
vasin
vasin

Reputation: 470

Strange nullPointerException in Java

I'm writing an app for Java ME, and I need a class for holding some data(PhoneBook). When I'm trying to launch this app, I'm always getting a nullPointerException. I'm calling the constructor of a class, and it allocates memory for 10 elements, so it shouldn't be null. What am I doing wrong? 

import javax.microedition.lcdui.*;
import javax.microedition.midlet.MIDlet;

public class TinyMIDlet extends MIDlet implements CommandListener {

    private PhoneBook phoneBook = new PhoneBook();

    public void initPhoneBook() {
        phoneBook.records[0].Name = new String("abc");        
    }

    protected void startApp() {
        initPhoneBook();
    }

    public class Record {
        public String Name;
        public String Number;
        public String email;
        public String Group;
    }

    public class PhoneBook {
        public Record[] records;

        PhoneBook() {
            records = new Record[10];
        }
    }
}

Upvotes: 0

Views: 173

Answers (3)

Tom
Tom

Reputation: 45104

phoneBook.records[0].Name = new String("abc");

should be

phoneBook.records[0] = new Record();
phoneBook.records[0].Name= new String("abc");// or  = "abc"

Upvotes: 4

violoncello
violoncello

Reputation: 11

I'm not reputable enough yet (heh) to edit Tom's detailed answer, but, to be precise

phoneBook.records[0] = new something();

should be 

phoneBook.records[0] = new Record();

Upvotes: 0

Brienne Schroth
Brienne Schroth

Reputation: 2457

The array of records isn't null, but each individual element of it is. You need to instantiate each element as well, right now it's just an array with 10 null entries.

Upvotes: 13

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