CODEWITHSUNDEEP
javaarraysmultithreading
D P.
D P.

Reputation: 1079

Inserting data in to a 2 dimensional byte[] array

I am new to Java and trying to use a two dimensional byte[ ] type. I have created a 2D byte[] array as shown bellow. But whenever I try to insert some data to it, it gives an error saying: NullPointerException

    byte[][][] Requisition = new byte[10][][];
    byte[] someinput = ("example").getBytes();
    Requisition[0][0]=someinput;
    System.out.println("Printing:" + Requisition[0][0].toString());
    etc..

Data type I am inserting in to this 2D array is type byte[] . Because what I am inserting is an encrypted data, these data will have the format of byte[ ] , not byte

I want Requisition array to hold two inputs for one line. For example

Requisition[0][1]=someinput1;
Requisition[0][2]=someinput2;

This someinput1 I am wanting to insert is not type byte. Data I am inserting will be byte[] type.

What I mean byte[] is (sequence of bytes using the platform's default charset, storing the result into a new byte array.)

Upvotes: 1

Views: 1091

Answers (3)

user3849220
user3849220

Reputation:

No, you didn't create a two dimension array. You created a three dimension array! -> byte[1][2][3]

If you want create a two dimension array, you need to declare the columns and cells of your table. That's only two values, not three like you did. For clarity look at this picture: http://www.php-kurs.info/grafik/xyz.png

A two dimension array you can declare and fill like that:

int rows = 10;
int cols = 10;
int[][] twoDimension = new int[rows][cols];

for (int i = 0; i < twoDimension.length; i++) {
    for (int j = 0; j < twoDimension[i].length; j++) {
        twoDimension[i][j] = // Value you want to fill!
    }
}

That's an array of int values. If you want create a byte array, you need to change the declaration of the array. 

byte[][] twoDimension = new byte[rows][cols];

Upvotes: 0

Justin k
Justin k

Reputation: 1104

It should be: 

byte[][][] someinput = new byte[5][5][5];

Then you can insert data in to this array.

Upvotes: 1

ChiefTwoPencils
ChiefTwoPencils

Reputation: 13940

When you do arr[n][m] you're accessing an element of whatever type arr is. In your case this is a byte. If you want to assign an array to a 2D array simply do:

Requisition[0] = someinput;

And...

    byte[][] Requisition = new byte[10][];
    byte[] someinput = ("example").getBytes();
    Requisition[0]=someinput;//These insertion will happens in a loop later

tested with...

    for (byte b : Requisition[0])
        System.out.println(b);

Of course, this answer is based on the fact you're not actually dealing with a 2D array, you have a 3D array which is likely a result of erroneous insertions of an array into a single element. If not, apply this logic to any n dimensional array.

Upvotes: 0

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