CODEWITHSUNDEEP
javaregex
szymon bonecki
szymon bonecki

Reputation: 119

How to split line using regular expression

I need to create regular expression which will split first line from file like this:

Array[0] = 0 
Array[1] = 2
Array[2] = 3

Here is a example of this file 

0 > 2 3
2 > 0 2
0 > 1 1
1 > 2 4

I tried doing this and it worked without blank characters like this 0>2 3 but I heard from my teacher that space between > is necessary.

My regular expression:

String[] wartosci = line.split(">|\\s");

How to do that?

Upvotes: 1

Views: 91

Answers (2)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626952

I think you need to split on any non-digit. So, use

String results[] = s.split("\\D+");

See the IDEONE demo

Here, \D+ matches 1 or more non-digit characters.

Java demo:

String s = "0 > 2 3";
String results[] = s.split("\\D+");
System.out.println(Arrays.toString(results));
// => [0, 2, 3]

Note that Avinash's [>\\s]+ is a whitelist approach, and if you plan to follow it, you might need to expand the character class with other symbols (like <, =, or even -...

And a couple of words about performance: your >|\\s regex is using one symbol alternation that is much less efficient that a character class [>\\s] that invloves much less backtracking (since it is compiled into 1 "entity" in the "regex internal program"). Whenever you wanted to match 1 symbol from a set of characters, use a character class.

Upvotes: 0

Manu
Manu

Reputation: 1485

String[] wartosci = line.split("[>\\s]+");

This will split on any sequence of > and whitespace characters. See documentation of Pattern

Upvotes: 1

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