How can I initialize an 2D array with 1D array?

Question

I just want to initialize a 2D array with 1D array values which is in a loop... like

for (int i=0; i<=x ; i++){  // x will be taken by user input(Scanner)
   for (int j=0; j<=3; j++){

     char s[][] = new char[x][6];
     System.out.println("Enter value a : ");
     a = input.nextInt();

     if (a==1){
        char r[] = {'A','B','C','D','E','F'};
        s[i][j] = r ;  // **Here is where I'm stuck at...**
     }
     else if (a==2){
       char r[] = {'G','H','I','J','K','L'};
       s[i][j] = r ;  // **Here is where I'm stuck at...**
     }
   }
}

I want my final 2D array as below for following the inputs x=2 a=1,a=2 &a=1

s[][]={{'A','B','C','D','E','F'},{'G','H','I','J','K','L'},{'A','B','C','D','E','F'}};

Please correct me If I was asking impossible one... Or provide me another method to get such result.... Thank you

s[i][j] = r would not be creating a 2d array. it'd be creating a 3 D array. s[i] = r would be 2d. — Marc B
– Marc B, Commented Aug 26, 2016 at 14:29
@MarcB a char[][] is a 2D array and a char[][][] is a 3D array. — SamTebbs33
– SamTebbs33, Commented Aug 26, 2016 at 14:38
Hint: next time use the preview function and properly indent / format your code snippets. You want us to help you, so you please make that easy as possible! — GhostCat
– GhostCat, Commented Aug 26, 2016 at 14:42

Frzn Flms · Accepted Answer · 2016-08-28 18:04:47Z

1

Change:

s[i][j] = r ;

to:

s[i] = r ;

Hopefully that should work.

s[i][j] is asking for a specified char in the 2D char array(because you're giving both dimensions, i being y and j being x). s[i] returns an entire row as an array. Since, you were looking to set row i to {'A', 'B', 'C', 'D', 'E', 'F'}, you should use s[i].

edited Aug 28, 2016 at 18:04

answered Aug 26, 2016 at 14:35

Frzn Flms

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2 Comments

SamTebbs33 Over a year ago

I suggest that you provide some info on how this works.

Frzn Flms Over a year ago

K, sorry I'm a little new :/

Tim Biegeleisen · Accepted Answer · 2016-08-26 14:41:22Z

0

You could accomplish want you want by using a jagged array:

char[][] s = new char[6][];

for (int i=0; i < 6; ++i) {
    int a = input.nextInt();

    if (a == 1) {
        s[i] = {'A','B','C','D','E','F'};
    }
    else if (a == 2) {
        s[i] = {'G','H','I','J','K','L'};
    }
}

It seemed that the spirit of what you were trying to do was to initialize a 2D array using 1D arrays in a loop. The above code snippet does that, using static 1D array initialization.

answered Aug 26, 2016 at 14:41

Tim Biegeleisen

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Comments

GhostCat · Accepted Answer · 2016-08-26 14:41:31Z

0

Here are some code examples to get you going:

char[][] matrix = new char[2][4];
for (int i=0; i < 2; i++) {
  // now create an array for the columns
  matrix[i]= new char[4];
  // now you could do
  for (int j=0; j < 4; j++) {
    matrix[i][j] = ...
  }
  // or
  char[] row = { '1', '2', '3', '4' };
  matrix[i] = row;
}

The idea is that you first say how many rows and columns you have. Then you iterate the first dimension, and you can set the values for the second dimension during each iteration. You can either set each cell using x/y coordinates; or you populate a whole row in one shot.

answered Aug 26, 2016 at 14:41

GhostCat

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