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Android

Posted by Dhruv Gupta
Dhruv Gupta
4,320 Points

Unexpected Null Pointer Exception when trying to set variable in another class

So I keep getting a Null Pointer Exception for god knows what reason.

My Code is below

public class MyRide {

    private ParseUser mCurrentUser;
    private ArrayList<ParseObject> mParseRides;
    private ParseQuery<ParseObject> mMyRides;
    private List<ParseObject> mRides;

    public Rides[] mRideList;

mCurrentUser = ParseUser.getCurrentUser();

        mMyRides = mCurrentUser.getRelation("MyRides").getQuery();
        mMyRides.orderByAscending("Year");
        mMyRides.findInBackground(new FindCallback<ParseObject>() {
            @Override
            public void done(List<ParseObject> rides, ParseException e) {
                if (e == null) {
                    mRides = rides;
                    Double[] StartLat = new Double[mRides.size()];
                    mRideList = new Rides[mRides.size()];


                    int i = 0;
                    for (ParseObject Ride : mRides) {
                        StartLat[i] = (Double) Ride.get("StartLat") ;
                       mRideList[i].setStartLat(StartLat[i]);
                         i++}
                  ...........
}

I get an error in the line

mRideList[i].setStartLat(StartLat[i])

java.lang.NullPointerException: Attempt to invoke virtual method 'void com.dhruv.ridealong.UI.MyRide.Rides.setStartLat(java.lang.Double)' on a null object reference

I know the StartLat[i] has a value because I've logged it and seen that it does. I've also tried manually putting a value.

My Rides class consists of 

public class Rides {

Double StartLat;

    public Double getStartLat() {
        return StartLat;
    }

    public void setStartLat(Double startLat) {
        StartLat = startLat;
    }
}

2 Answers

Steve Hunter
Steve Hunter
57,712 Points
Steve Hunter
Steve Hunter
57,712 Points

Hi Dhruv,

I think it's saying that mRideList[i] might be null - difficult to say. Do you have this in a git repo that I can pull down to replicate the error?

Steve.

P.S. I edited your post to make the code easier to read.

Dhruv Gupta
Dhruv Gupta
4,320 Points

Nope :P

I really should take the Git class here, but have never gotten around to it.

Is there anything in particular you would want me to post? I put what I considered relevant code, and both of the two classes above are extremely abridged.

Dhruv Gupta
Dhruv Gupta
4,320 Points
Dhruv Gupta
Dhruv Gupta
4,320 Points

Yo I got it,

So I initiated my array, but every element inside of it was null

So I added the line in the for command mRideList[i] = new Rides();

Steve Hunter
Steve Hunter
57,712 Points

I suspected that was where the problem was!

Glad you got it fixed.