Java - Split List<String> into... sublist?

Question

I'm really not sure how to best ask this, so hopefully someone can figure out what I'm talking about.

Assume a List that looks something like this:

[
    "Harum beatae autem occaecati. Incidunt quis",
    "eius perferendis itaque dolorum dolores doloribus.",
    "Veniam voluptate mollitia\net aut qui magnam. Ut",
    "quos unde nulla qui. Earum odit dolores non illo illum."
]

I want to split it at the "\n" like so :

[
    "Harum beatae autem occaecati. Incidunt quis",
    "eius perferendis itaque dolorum dolores doloribus.",
    "Veniam voluptate mollitia",
    "et aut qui magnam. Ut",
    "quos unde nulla qui. Earum odit dolores non illo illum."
]

@LuiggiMendoza One of the strings has been split. The output list has five strings instead of four. — khelwood
– khelwood, Commented Aug 7, 2018 at 14:53
Input is four lines with a "\n" halfway through the third, output is five lines split at the newline — Evertiro
– Evertiro, Commented Aug 7, 2018 at 14:53

Youcef LAIDANI · Accepted Answer · 2018-08-07 14:54:05Z

10

If you are using Java 8 you can use stream and flatMap like this :

List<String> result = list.stream()
        .flatMap(s -> Arrays.stream(s.split("\n")))
        .collect(Collectors.toList());

If not you can use a simple loop like so :

List<String> result = new ArrayList<>();
for (String s : list){
    result.addAll(Arrays.asList(s.split("\n")));
}

answered Aug 7, 2018 at 14:54

Youcef LAIDANI

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13 Comments

Evertiro Over a year ago

I am actually using Java 8, the first option throws this error: Cannot infer type argument(s) for <R> flatMap(Function<? super T,? extends Stream<? extends R>>)

Evertiro Over a year ago

Second option seems to work (but throws a security warning) but crashes on run

Praveen Shendge Over a year ago

Small Correction : s.split("\n") should be s.split("\\n")

Youcef LAIDANI Over a year ago

@DanGriffiths this is not possible check the demo of java 8 solution and a demo of simple loop

Youcef LAIDANI Over a year ago

@zlakad I read before a nice book I would suggest to read it It explain how flatMap and every this how its work with an intelligent way the book is Java 8 Lambdas hope this can help you ;)

|

Praveen Shendge · Accepted Answer · 2018-08-07 15:18:01Z

0

Try this one.

 public List<String> extractNewLineSeparatedStrings(String input) {

      List<String> result = new ArrayList<String>();        
      if (input != null) {
        // split by new line
        String[] arr = input.split("\\n");
        result =  Arrays.asList(arr);
      }
      return result;
  }

edited Aug 7, 2018 at 15:18

answered Aug 7, 2018 at 15:01

Praveen Shendge

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1 Comment

Evertiro Over a year ago

You're expecting a string input, I'm starting with a List

Rence Abishek · Accepted Answer · 2018-08-07 15:36:59Z

0

Adding another way(simple) to achieve, using StringTokenizer

List<String> result = new ArrayList<>();
for (String s : list){
   StringTokenizer st = new StringTokenizer(s,"\n");  
   while(st.hasMoreTokens()) {
   result.add(st.nextToken());
}
}

edited Aug 7, 2018 at 15:36

answered Aug 7, 2018 at 15:14

Rence Abishek

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5 Comments

Evertiro Over a year ago

Interestingly, the code as provided does nothing. If I use \\n instead of \n, it breaks at every instance of 'n'... with or without the slash

Evertiro Over a year ago

Just did a test, changed it to match "%n" and it split at every instance of "n" as well. Oops?

Rence Abishek Over a year ago

pls send your correct input. i tried my answer in IDE and it is working fine

Evertiro Over a year ago

Right now my input is this: List<String> unformattedText = fontRenderer.listFormattedStringToWidth(inputText, maxWidth - 10); Where inputText is: inputText<String> = "Harum beatae\n autem occaecati."

Rence Abishek Over a year ago

let me see how you tried in your coding. cause this would surely work

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