How to split multi-line string in Java

Question

I have the following data text :

[data]A[/data]
aaa
4 5 8 
[data]B[/data]
bbb
3 1 9 
[data]C[/data]
ccc
6 5 2
...

I want to split them in to the following 3 units :

1st unit :

[data]A[/data]
aaa
4 5 8

2nd unit :

[data]B[/data]
bbb
3 1 9

3rd unit :

[data]C[/data]
ccc
6 5 2

So my code looks like this :

String Units[]=dataText.split("[data]");

Yet, this doesn't do it properly, what's the right way to split it ?

If I use regex, how should I write the expression ?

Possible duplicate of Java String.split() Regex

Van_Cleff
– Van_Cleff

2019-03-01 20:53:04 +00:00
Commented Mar 1, 2019 at 20:53 — Van_Cleff
– Van_Cleff, Commented Mar 1, 2019 at 20:53

Andreas · Accepted Answer · 2019-03-01 21:12:12Z

3

Use regex (?ms)(?<=.)(?=^\[):

    String[] units = dataText.split("(?ms)(?<=.)(?=^\\[)");

See regex101.com for demo.

Explanation:

(?ms)       Turn on MULTILINE ('^' and '$' match after/before line terminator)
                and DOTALL (aka "single line", '.' matches any character)
(?<=.)      Must be preceded by a character (needs 's' flag)
               Used to prevent matching very first '['
(?=^\[)     Must be followed by a '[' at the beginning of a line (needs 'm' flag)

edited Mar 1, 2019 at 21:12

answered Mar 1, 2019 at 21:04

Andreas

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Comments

Christian Huber · Accepted Answer · 2019-03-01 21:32:18Z

1

You could use a BufferedReader:

BufferedReader br = new BufferedReader(new StringReader(dataString));

Iterate the String like this:

int lineCounter = 0;
int arrayCounter = 0;
String line = null;
while( (line = br.readLine()) != null )
{
    units[arrayCounter] += line;
    if (lineCounter >= 2) {
        arrayCounter++;
        lineCounter = 0;
    }
}

edited Mar 1, 2019 at 21:32

answered Mar 1, 2019 at 20:56

Christian Huber

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5 Comments

Frank Over a year ago

OK, but how to decide the size of units ? My dataString could include hounds of units.

Christian Huber Over a year ago

Your example looked like 3 lines per unit. If this size is not constant, you will have to use a regex.

Christian Huber Over a year ago

Yes, it is a clean solution.

Frank Over a year ago

What I meant was, each unit has 3 lines, that's fixed, but there could be 216 units or 567 units, so how to create "String units=new String[ ??? ]"

Christian Huber Over a year ago

You have to use a collection like ArrayList.

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