How do I fix this source not found error? Reading text file with buffered reader - Java

Im trying to read deck.txt which is in the src directory of the application. The error I get is:

Exception in thread "main" java.lang.NullPointerException at Deck.(Deck.java:15) at TwentyOne.main(TwentyOne.java:7)

Line 7 in TwentyOne is just:

Deck deck = new Deck();

The file has a single integer on each line and is 104 lines long.

Where cards[i].suit.... is the line throwing the exception

try (BufferedReader br = new BufferedReader(new FileReader("src/deck.txt"))) {   
        for (int i = 0; i < 104; i++) {                 
            cards[i].suit = Integer.parseInt(br.readLine());
            cards[i].rank = Integer.parseInt(br.readLine());
        }

    } catch (IOException e) {
        e.printStackTrace();
    }

To try see what was wrong I copied this code out of eclipse into another directory with the file, this time just println(br.readLine()) rather than assigning it to the array and it worked fine.

Have I got the file in the wrong location or is there something else I'm missing? Thanks for your help