How Do I Split A String By Line Break?

Question

I'm a noob to android development and I am trying to split a string multiple times by its multiple line breaks. the string I'm trying to split is pulled from a database query and is constructed like this:

public String getCoin() {
    // TODO Auto-generated method stub
    String[] columns = new String[]{ KEY_ROWID, KEY_NAME, KEY_QUANTITY, KEY_OUNCES, KEY_VALUE };
    Cursor c = ourDatabase.query(DATABASE_TABLE, columns, null, null, null, null, null);
    String result = "";

    int iRow = c.getColumnIndex(KEY_ROWID);
    int iName = c.getColumnIndex(KEY_NAME);
    int iQuantity = c.getColumnIndex(KEY_QUANTITY);
    int iOunces = c.getColumnIndex(KEY_OUNCES);
    int iValue = c.getColumnIndex(KEY_VALUE);

    for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
        result = result + /*c.getString(iRow) + " " +*/ c.getString(iName).substring(0, Math.min(18, c.getString(iName).length())) + "\n";
    }
    c.close();
    return result;

result.getCoin reads as this:

alphabravocharlie

I want to split the string at the line break and place each substring into a String Array. This is my current code:

String[] separated = result.split("\n");
      for (int i = 0; i < separated.length; i++) {
           chartnames.add("$." + separated[i] + " some text" ); 
           }

This gives me an output of:

"$.alpha
bravo
charlie some text"

instead of my desired output of:

"$.alpha some text, $.bravo some text, $.charlie some text"

Any help is greatly appreciated

You show output, without showing us the input, which does not help. — CommonsWare, Nov 20 '12 at 00:44
This means your input does not contain the `\n` character so the String isn't split. Check whether the input contains `\r\n` (if source comes from MS windows for ex.) — JScoobyCed, Nov 20 '12 at 00:47
@JScoobyCed please check my edit I add \n to my string before i return result so it shout contain \n — B. Money, Nov 20 '12 at 00:55
Do you mean "$.alpha\nbravo\ncharlie some text"? Because your existing output doesn't make any sense. — Jherico, Nov 20 '12 at 00:55
Yes. that's what I'm talking about. How can i clarify my question? — B. Money, Nov 20 '12 at 00:57
I updated the question. Make sure that's the correct unexpected output though. — Jherico, Nov 20 '12 at 01:05
I just tried constructing a `result` and then splitting it using your posted code and it worked perfectly well. Are you sure the code you posted is what's producing these results? — Ted Hopp, Nov 20 '12 at 01:12
Dup of http://stackoverflow.com/questions/454908/split-java-string-by-new-line — Vadzim, Oct 05 '14 at 17:37

score 60 · Accepted Answer · edited Apr 29 '16 at 21:31

60

you can split a string by line break by using the following statement :

   String textStr[] = yourString.split("\\r\\n|\\n|\\r");

edited Apr 29 '16 at 21:31

Community

1
1

answered Nov 20 '12 at 00:46

RajeshVijayakumar

10,281
11
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84

12

That won't work for text from a Mac, where the line terminator is `\r`. – Ted Hopp Nov 20 '12 at 00:48
I think based on OS the terminator can be decided. The above solution will work only for windows IMO. – B. S. Rawat Mar 07 '16 at 16:45
1

How about yourString.split(System.lineSeparator()); – adn.911 Apr 23 '17 at 09:08
1

@adn.911: `System.lineSeparator()` is platform-dependent, so you can use it only when you know, what line separator will be in your input. – Xdg Sep 16 '17 at 11:30
Shorter: `"\r?\n|\r"` – Leponzo Dec 10 '21 at 16:05

Ted Hopp · Answer 2 · 2018-04-25T02:57:09.887

19

It's a little overkill, but you can use the standard I/O classes:

BufferedReader rdr = new BufferedReader(new StringReader(result));
List<String> lines = new ArrayList<String>();
for (String line = rdr.readLine(); line != null; line = rdr.readLine()) {
    lines.add(line);
}
rdr.close(); // good form to close streams, but unnecessary for StringReader

// lines now contains all the strings between line breaks of any type

The advantage of this is that BufferedReader.readLine() has all the logic worked out for detecting all sorts of line terminators.

As of Java 8, BufferedReader has a lines() method, so there's an easier way (thanks, @jaco0646):

List<String> lines = new BufferedReader(new StringReader(result))
                         .lines()
                         .collect(Collectors.toList();

or, if an array is needed instead:

String[] lines = new BufferedReader(new StringReader(result))
                     .lines()
                     .toArray(String[]::new);

edited Apr 25 '18 at 02:57

answered Nov 20 '12 at 00:51

Ted Hopp

232,168
48
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521

This is even simpler in Java 8, which added a [lines() method](https://docs.oracle.com/javase/8/docs/api/java/io/BufferedReader.html#lines--). – jaco0646 Apr 24 '18 at 22:19
Also note there's not a lot of benefit in [closing a StringReader](https://stackoverflow.com/questions/6122013/should-i-close-a-stringreader). – jaco0646 Apr 24 '18 at 22:23
@jaco0646 - Yes, Java 8 does make it a bit easier. I'll update my answer to show that. Thanks. As to closing the `StringReader`, that was just me on autopilot (closing any stream once I'm done with it). I'm surprised I didn't stick the whole thing into a `try/finally` statement. :) – Ted Hopp Apr 25 '18 at 02:42

score 5 · Answer 3 · edited Mar 07 '16 at 16:36

5

Using the Apache commons helper class StringUtils.

The platform independent way:

String[] lines = StringUtils.split(string, "\r\n");

The platform dependent way. Maybe some CPU cycles faster. But I wouldn't expect it to matter.

String[] lines = StringUtils.split(string, System.lineSeparator());

edited Mar 07 '16 at 16:36

keiki

3,260
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answered Nov 06 '15 at 20:21

snakedoctor

185
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8

score 2 · Answer 4 · answered Nov 20 '12 at 01:02

2

If possible I would suggest using the Guava Splitter and Joiner classes in preference to String.split. But even then, it's important to make sure that you're properly escaping your regular expressions when declaring them. I'm not certain "\n" won't be properly interpreted by the regex compiler in Java, but I'm not sure it will be either.

Covering all possible line endings is tricky, since multiple consecutive EOL markers can mess up your matching. I would suggest

String [] separated = result.replaceAll("\\r", "").split("\\n");

answered Nov 20 '12 at 01:02

Jherico

28,584
8
61
87

I had no success with this. Should i just try to split by last character before line break or somthing like that? – B. Money Nov 20 '12 at 01:07
If you had no success your input probably does not contain new lines. Perhaps you could post the contents of `result.getBytes()'? – Jherico Nov 20 '12 at 01:10
5

If you want to deal with all combinations of "\r" "\n" "\r\n" "\n\r" you can use: Splitter.on(CharMatcher.anyOf("\n\r")).omitEmptyStrings().split(yourstring); (note that this will also drop empty lines, which may or may not be what you want) – joe p May 20 '15 at 02:33

score 1 · Answer 5 · edited Feb 18 '15 at 09:54

1

Matcher m = Pattern.compile("(^.+$)+", Pattern.MULTILINE).matcher(fieldContents);

while (m.find()) {
    System.out.println("whole group " + m.group())
}

edited Feb 18 '15 at 09:54

blalasaadri

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answered Feb 18 '15 at 08:45

Dzmitry Karalevich

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3

score 0 · Answer 6 · answered Sep 03 '15 at 11:12

0

I propose the following snippet, which is compatiple with PC and Mac endline styles both.

String [] separated = result.replaceAll("\\r", "\\n")
   .replaceAll("\\n{2,}", "\\n")
   .split("\\n");

answered Sep 03 '15 at 11:12

anton

247
3
13

With this solution, blank lines in the input will disappear. – Ted Hopp Oct 01 '15 at 18:47

How Do I Split A String By Line Break?

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