Iterate through an object- Android Java

Question

I am trying to go through an object which has an array within it containing names and numbers of -

 public void showPlayerGameList(){
        playerTextView = findViewById(R.id.aPlayerBox);

        for(PlayerDetails aPlayer : playerListGame.myPlayers) {

            playerTextView.append(aPlayer.name + "\n");
        }
    }
}

But I get the following error:

Caused by: java.lang.NullPointerException: Attempt to read from field 'java.lang.String com.example.android.footysortit.PlayerDetails.name' on a null object reference

The way I am adding my player which is an object of PlayerDetails (which just contains a 2x String and an Int):

            if(phone.moveToFirst()) {
                PlayerDetails player = new PlayerDetails(); //TODO turn this into a loop to add each player the user picks and then display it
                player.name = phone.getString(phone.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));
               // player.number =phone.getString(phone.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER));
                playerListGame.addPlayer(player);

The idea is for the user to pick a contact and their name displays within a list but they can pick different contacts each time and each contact should be added to the list.

Any ideas?

Thank you

debug and check that phone.getString(phone.getColumnIndex(); is returning someting or not — Sunil Soni, Mar 26 '18 at 12:47
According to error message it's look like user object is null so when you try to access name field of null object you get NPE. — contrapost, Mar 26 '18 at 12:52
Possible duplicate of [What is a NullPointerException, and how do I fix it?](https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) — M. Prokhorov, Mar 26 '18 at 13:00
@contrapost3 - public class PlayerDetails { int id; String name; String number; } — , Mar 26 '18 at 13:00
@SunilSoni The getString does return something. If i use the following: playerListGame.addPlayer(player); playerTextView = findViewById(R.id.aPlayerBox); playerTextView.append(player.name); It prints the name that I choose from the contacts list. — , Mar 26 '18 at 13:08
Therefore the only thing left we didn't see you initialise is `playerListGame.addPlayer(...)`. Where do you initialise the `playerListGame` Object? Try to log if it's value is null or not — L.Spillner, Mar 26 '18 at 13:10
@L.Spillner I initialise is globally within the same class... — , Mar 26 '18 at 13:17

Sam · Accepted Answer · 2018-03-26T13:00:39.583

0

When you are adding your players, check that the result of phone.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME) isn't null.

Currently it seems like a null value is set as the players name.

Perhaps there is another value you can try instead, or set the name to an empty string instead of null.

edited Mar 26 '18 at 13:00

answered Mar 26 '18 at 12:48

Sam

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Hi, thanks for your reply. If i use the follow: playerListGame.addPlayer(player); playerTextView = findViewById(R.id.aPlayerBox); playerTextView.append(player.name); It works, so it shows that the player.name does hold a value. The name will appear in the text view – Mar 26 '18 at 13:06
are you setting the value of player.name anywhere else? – Sam Mar 26 '18 at 13:09
Good question, I actually made player global at the start, so I moved it into my function and made it local. So every time they choose a contact it will now pass through the name and if they do it again, it will print the second name on another line. – Mar 26 '18 at 13:17
Do you make and add to playerListGame.myPlayers a PlayerDetails, without setting a name on it anywhere? – Sam Mar 26 '18 at 13:21
Yea, so I create playerListGame object from the class PlayerList( which creates array of PlayerDetails called myPlayers) The idea is then to add a player to playerListGame with their contact details and then use playerListGame.myPlayers[i] to display their name. So while writing this I just noticed that I should be using: playerTextView.append(playerListGame.myPlayers[0].name+"\n"); and then maybe use a for loop to display the names.... – Mar 26 '18 at 13:27
Glad we were able to work through it! – Sam Mar 26 '18 at 13:32
Same here, thanks for your help! – Mar 26 '18 at 13:54

Iterate through an object- Android Java

1 Answers1