Convert String into 2D int array

Question

I have problem with conversion from String into two dimension int array.
Let's say I have:

String x = "1,2,3;4,5,6;7,8,9"

(In my program it will be String from text area.) and I want to create array n x n

int[3][3] y = {{1,2,3},{4,5,6},{7,8,9}}

(Necessary for next stages.) I try to split the string and create 1 dimensional array, but I don't have any good idea what to do next.

As you suggest I try split at first using ; then , but my solution isn’t great. It works only when there will be 3 x 3 table. How to create a loop making String arrays?

public int[][] RunMSTFromTextFile(JTextArea ta)
    {
        String p = ta.getText();
        String[] tp = p.split(";");

        String tpA[] = tp[0].split(",");
        String tpB[] = tp[1].split(",");
        String tpC[] = tp[2].split(",");

        String tpD[][] = {tpA, tpB, tpC};

        int matrix[][] = new int[tpD.length][tpD.length];

        for(int i=0;i<tpD.length;i++)
        {
            for(int j=0;j<tpD.length;j++)
            {
                matrix[i][j] = Integer.parseInt(tpD[i][j]);
            }
        }
        return matrix;
    }

you must use split by ; and then for each entry in the array split by , — Miquel
– Miquel, Commented Jan 24, 2013 at 22:51
Using split as you say sounds like an idea that could go further. — madth3
– madth3, Commented Jan 24, 2013 at 22:51
when I use only comma for spliting: ' public int[] RunMSTFromTextFile(JTextArea ta) { String p = ta.getText(); String[] tp = p.split(","); int matrix[] = new int[tp.length]; for(int i=0;i<tp.length;i++) { matrix[i] = Integer.parseInt(tp[i]); } return matrix; } — user2009164
– user2009164, Commented Jan 24, 2013 at 23:00

Mel Nicholson · Accepted Answer · 2021-12-20 15:20:18Z

3

After using split, take a look at Integer.parseInt() to get the numbers out.

String lines[] = input.split(";");
int width = lines.length;
String cells[] = lines[0].split(",");
int height = cells.length;
int output[][] = new int[width][height];

for (int i=0; i<width; i++) {
    String cells[] = lines[i].split(",");
    for(int j=0; j<height; j++) {
        output[i][j] = Integer.parseInt(cells[j]);
    }
}

Then you need to decide what to do with NumberFormatExceptions

edited Dec 20, 2021 at 15:20

answered Jan 24, 2013 at 23:00

Mel Nicholson

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2 Comments

user1181445 Over a year ago

I believe you meant to say String cells[].

ChargerIIC Over a year ago

Just converted to C# and fixed a problem for me. Thanks!

Andrew Thompson · Accepted Answer · 2013-01-24 23:10:53Z

3

Split by ; to get rows.
Loop them, incrementing a counter (e.g. x)
1. Split by , to get values of each row.
2. Loop those values, incrementing a counter (e.g. y)
  - Parse each value (e.g. using one of the parseInt methods of Integer) and add it to the x,y of the array.

edited Jan 24, 2013 at 23:10

answered Jan 24, 2013 at 23:00

Andrew Thompson

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1 Comment

Mel Nicholson Over a year ago

+1 leading without spoonfeeding. Probably should include the name of the parse method.

Miserable Variable · Accepted Answer · 2013-01-24 23:02:25Z

2

If you have already created an int[9] and want to split it into int[3][3]:

for (int i = 0; i < 3; i++) {
  for (int j = 0; j < 3; j++) {
    toArray[i][j] = fromArray[(3*i) + j);
  }
}

Now, if the 2-dimensional array is not rectangular, i.e. the size of inner array is not same for all outer arrays, then you need more work. You would do best to use a Scanner and switch between nextString and next. The biggest challenge will be that you will not know the number of elements (columns) in each row until you reach the row-terminating semi-colon

edited Jan 24, 2013 at 23:02

answered Jan 24, 2013 at 22:50

Miserable Variable

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Comments

Miquel · Accepted Answer · 2013-01-24 23:18:58Z

0

A solution using 2 splits:

String input = "1,2,3;4,5,6;7,8,9";

String[] x = input.split(";");

String[][] result = new String[x.length][];
for (int i = 0; i<x.length; i++) {
    result[i] = x[i].split(",");
}

This give a 2 dimension array of strings you will need to parse those ints afterwards, it depends on the use you want for those numbers. The following solution shows how to parse them as you build the result:

String input = "1,2,3;4,5,6;7,8,9";

String[] x = input.split(";");

int[][] result = new int[x.length][];

for (int i = 0; i < x.length; i++) {
    String[] row = x[i].split(",");
    result[i] = new int[row.length];

    for(int j=0; j < row.length; j++) {
        result[i][j] = Integer.parseInt(row[j]);
    }
}

edited Jan 24, 2013 at 23:18

answered Jan 24, 2013 at 23:02

Miquel

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Comments

Komal12 · Accepted Answer · 2017-10-23 05:44:50Z

0

Super simple method!!!

package ADVANCED;
import java.util.Arrays;
import java.util.Scanner;

public class p9 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner sc=new Scanner(System.in);

        String x=sc.nextLine();
        String[] array = x.split(",");
        int length_x=array.length;
        int[][] two=new int[length_x/2][2];

        for (int i = 0; i <= length_x-1; i=i+2) {
            two[i/2][0] = Integer.parseInt(array[i]);
        }

        for (int i = 1; i <= length_x-1; i=i+2) {
            two[i/2][1] = Integer.parseInt(array[i]);
        }   
    }
}

edited Oct 23, 2017 at 5:44

Komal12

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answered Oct 23, 2017 at 5:30

Minsoo KIm

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