Reading in integers to a 2D array

Question

I need help with reading integers into a 2D square array of N x N dimensions.

For example, if the user input is:

123  
333  
414

Then I will need an array:

{
 {1, 2, 3}, 
 {3, 3, 3}, 
 {4, 1, 4}
}

The problem that I am having is that there is no space between these integers. If there were a space, I could just do

for (int i = 0 ; i < N; i++) {
    for(int j = 0; j < N ; j++) {
        myArray[i][j] = scan.nextInt();
    }
}

I approached this problem by trying to use substrings and parsing it into the array, although I did not get anywhere.

Another approach (Edit)

for (int i = 0; i < N; i++) {
    for (int j = 0; j < N; j++) {
        myArray[i][j] = Integer.parseInt(scan.nextLine().substring(j, j+1));
    }
}

This does not work either - it keeps running after the three lines are entered.

Read your input as String, convert it with `toCharArray` method and then add to your 3-dimensional array. — DimaSan, Jan 14 '17 at 17:45
http://stackoverflow.com/questions/33696011/how-to-use-split-a-string-after-a-certain-length — nicomp, Jan 14 '17 at 17:45
Is there any way to keep this as a two-dimensional int array? I just added another approach that I think could work. — , Jan 14 '17 at 17:46
***there is no space between these integers...***....are those ints between 0 and 9 then??? — ΦXocę 웃 Пepeúpa ツ, Jan 14 '17 at 17:49
In Java 8 you could use `"123".chars().map(ch -> ch-'0').toArray();` which returns `[1, 2, 3]` array of integers. But be sure that string really contains only digits. Use this approach for each row. — Pshemo, Jan 14 '17 at 17:57
`scan.nextLine()` statment is running `N*N` times , so it requires N*N new line inputs — Rajmani Arya, Jan 14 '17 at 18:03
Try this `for (int i = 0; i < N; i++) { String s = scan.nextLine(); for (int j = 0; j < N; j++) { myArray[i][j] = Integer.parseInt(substring(j, j+1)); } }` — Rajmani Arya, Jan 14 '17 at 18:04

J. Pichardo · Answer 1 · 2017-01-14T19:00:28.547

Perhaps this helps:

public static void main( String[] args ) {

    Scanner scanner = new Scanner( System.in );

    int[][] array = new int[3][3];

    for ( int[] ints : array ) {
        char[] line = scanner.nextLine().toCharArray();
        for ( int i = 0; i < line.length; i++ ) {
            ints[i] = Character.getNumericValue( line[i] );
        }
    }

    Arrays.stream( array ).forEach( x -> System.out.println( Arrays.toString( x ) ) );
}

Also with Java 8

public static void main( String[] args ) {

    Scanner scanner = new Scanner( System.in );

    int[][] array = new int[3][3];

    for ( int[] ints : array ) {
        ints = scanner.nextLine().chars().map( Character::getNumericValue ).toArray();
    }

    Arrays.stream( array ).forEach( x -> System.out.println( Arrays.toString( x ) ) );
}

Shehan V · Answer 2 · 2017-01-14T18:16:44.580

0

The reason is java scanner gets whole number (e.g:123) as a one number.

for (int i = 0 ; i < N; i++) {
        int p = scan.nextInt();
        for (int j = N-1; j >= 0; j--) {
            array[i][j] = p % 10;
            p = p / 10;
        }
    }

edited Jan 14 '17 at 18:16

answered Jan 14 '17 at 18:07

Shehan V

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Reading in integers to a 2D array

2 Answers2