Question

I’m making a dice game for android and i have this loop that fills an array with the numbered rolled at roll “j”. It went like this

int[] rolls = new int[6];
    for (int j : rolls) {
        rolls[j] = (int) (Math.random() * 5);
        rolls[j]++;
        Log.i(getClass().getName(), "Rolls[" + j + "] = " + rolls[j]);
    }

Except the output (in the logfile is this)

Rolls[0] = 4
Rolls[0] = 2
Rolls[0] = 3
Rolls[0] = 6
Rolls[0] = 3
Rolls[0] = 4

And when i change the code to this

int[] rolls = new int[6];
    for (int j = 0; j < rolls.length ; j++) {
        rolls[j] = (int) (Math.random() * 5);

        rolls[j]++;
        Log.i(getClass().getName(), "Rolls[" + j + "] = " + rolls[j]);
    }

the output is correct

Rolls[0] = 4
Rolls[1] = 2
Rolls[2] = 3
Rolls[3] = 6
Rolls[4] = 3
Rolls[5] = 4

I must be doing something stupid somewhere.

Answer 1

The statement:

 for (int j : rolls) 

Iterates over the entries in rolls, not the indices. Since arrays are initialized to 0 in Java, the value j is zero for each of the 6 iterations.