3D array output null in java?

Question

So I just learned doing arrays in 1D and 2D in java, but I don't seem to do 3D correct since the output seems to show null like this:

One null null
null Two null
null null Three

One null null
null Two null
null null Three

One null null
null Two null
null null Three

---

I want it like this:

One Two Three
One Two Three
One Two Three

One Two Three
One Two Three
One Two Three

One Two Three
One Two Three
One Two Three

---

SOLVED (changed the format of the array to make it simplier for me as a beginner.)

    public class Main {
    public static void main(String[] args)
    {
        String[][][] numbers = {
                                {{"One", "Two", "Three"}, {"Four", "Five", "Six"},
                                {"Seven", "Eight", "Nine"}, {"Ten", "Eleven", "Twelve"}}
                                };

        for(int i = 0; i < numbers.length; i++)
        {
            System.out.println();
            for(int j = 0; j < numbers[i].length; j++)
            {
                System.out.println();
                for(int k = 0; k < numbers[i][j].length; k++)
                {
                    System.out.print(numbers[i][j][k] + " ");
                }
            }
        }
    }
}

Answer 1

You've got to fill your arrays correctly. A 3D-array in Java is just an array of 2D-arrays and a 2D-array is just an array of (1D-)arrays.

You can fill a given (1D-)array row of length 3 by assigning values to its elements, that is

row[0] = "One";
row[1] = "Two";
row[2] = "Three";

Given a 2D-Array matrix you can do this for every single row:

for (String[] row : matrix) {
    row[0] = "One";
    row[1] = "Two";
    row[2] = "Three";
}

Now, you have an array numbers of those matrices:

for (String[][] matrix : numbers) {
    for (String[] row : matrix) {
        row[0] = "One";
        row[1] = "Two";
        row[2] = "Three";
    }  
}

I've used for-each-loops here. They can be turned into normal for-loops easily:

for (int i = 0; i < numbers.length; i++) {
    String[][] matrix = numbers[i];
    for (int j = 0; j < matrix.length; j++) {
        String[] row = matrix[j];
        row[0] = "One";
        row[1] = "Two";
        row[2] = "Three";
    }
}

From that you can substitute row by matrix[j] which gives you

for (int i = 0; i < numbers.length; i++) {
    String[][] matrix = numbers[i];
    for (int j = 0; j < matrix.length; j++) {
        matrix[j][0] = "One";
        matrix[j][1] = "Two";
        matrix[j][2] = "Three";
    }
}

Of course, you can substitute matrix, too. This time by numbers[i]:

for (int i = 0; i < numbers.length; i++) {
    for (int j = 0; j < numbers[i].length; j++) {
        numbers[i][j][0] = "One";
        numbers[i][j][1] = "Two";
        numbers[i][j][2] = "Three";
    }
}

Update

You can directly integrate this in your code:

public class Main {
    public static void main(String[] args)
    {
        String[][][] numbers = new String[3][3][3];
        for (int i = 0; i < numbers.length; i++) {
            for (int j = 0; j < numbers[i].length; j++) {
                numbers[i][j][0] = "One";
                numbers[i][j][1] = "Two";
                numbers[i][j][2] = "Three";
            }
        }        

        for(int i = 0; i < numbers.length; i++)
        {
            System.out.println();
            for(int j = 0; j < numbers[i].length; j++)
            {
                System.out.println();
                for(int k = 0; k < numbers[i][j].length; k++)
                {
                    System.out.print(numbers[i][j][k] + " ");
                }
            }
        }
    }
}