CODEWITHSUNDEEP
javaandroidlist
Mornor
Mornor

Reputation: 3793

Null String from nowhere.

I have a basic ArrayList<Car> and I want to use it to make a String[]. Pretty easy, but I get a null in my String from nowhere, and I do not understand the problem.
Here is my function. 

private String[] makeListOfCars(){
        Log.d("1st Car brand ", user.getCars().get(0).getBrand());
        Log.d("2nd Car brand ", user.getCars().get(1).getBrand());
        String result[] = new String[user.getCars().size()]; // Size > 0 because the user have at least one car here
        for(int i = 0 ; i < user.getCars().size() ; i++){
            result[i] += user.getCars().get(i).getBrand() + " " + user.getCars().get(i).getModel();
            Log.d("Result ", result[i]);
        }
        return result;
    }

And here is the output I get:

03-04 13:49:32.470 27216-27216/com.example.bla.app D/1st Car brand﹕ Bmw
03-04 13:49:32.470 27216-27216/com.example.bla.app D/2nd Car brand﹕ Volvo
03-04 13:49:32.470 27216-27216/com.example.bla.app D/Result﹕ nullBmw 335i
03-04 13:49:32.470 27216-27216/com.example.bla.app D/Result﹕ nullVolvo V40

Can someone explain me from where this null come from?

Upvotes: 2

Views: 79

Answers (1)

Eran
Eran

Reputation: 393856

Change

result[i] += user.getCars().get(i).getBrand() + " " + user.getCars().get(i).getModel();

to

result[i] = user.getCars().get(i).getBrand() + " " + user.getCars().get(i).getModel();

The "null" is appended because the initial value of result[i] is null, and when you concatenate a null value to a String, the null becomes the "null" String.

Upvotes: 4

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