Split string into matrix array

Question

I have a String:

1,3,4,5,
1,4,5,0,
2,5,3,8,

That I want to store in a variable matrix (int[][]). What is the best way to accomplish this? Should I use the String class' methods? Or should I use a Regex?

Community · Accepted Answer · 2017-05-23 12:19:53Z

6

First (by String.split(..)) split on newline, then split the items of each of the resultant array on ,. Then parse each using Integer.parseInt(..)

edited May 23, 2017 at 12:19

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answered Mar 19, 2011 at 23:50

Bozho

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WhiteFang34 · Accepted Answer · 2011-03-20 09:55:11Z

2

String input = "1,3,4,5,\n1,4,5,0,\n2,5,3,8,";

String[] str1 = input.split("\n");
int[][] matrix = new int[str1.length][];
for (int i = 0; i < matrix.length; i++) {
    String[] str2 = str1[i].split(",");
    matrix[i] = new int[str2.length];
    for (int j = 0; j < matrix[i].length; j++) {
        matrix[i][j] = Integer.parseInt(str2[j]);
    }
}

edited Mar 20, 2011 at 9:55

answered Mar 20, 2011 at 0:01

WhiteFang34

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3 Comments

Bozho Over a year ago

StringTokenizer is de-facto deprecated: "It is recommended that anyone seeking this functionality use the split method of String or the java.util.regex package instead."

WhiteFang34 Over a year ago

Hmm that's interesting that the JavaDoc actually recommends that now, didn't realize that. It seems like it's best to avoid regex where possible though. As well StringTokenizer is 3 times faster in this case (10k iterations) and does less object creation, although likely doesn't matter.

WhiteFang34 Over a year ago

Replaced StringTokenizer with String.split() as suggested.

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