递归将字符串拆分为固定数量的单词[Java] [英] Split String into Fixed Number of Words Recursively [Java]

问题描述

我试图递归地将String(存储在ArrayList中)分成固定数目的单词(不是字符).

I am attempting to split a String (stored in ArrayList) into fixed number of words (not characters) recursively.

例如，假设我有一个ArrayList，其中包含以下两个String短语:

For example, suppose I have the an ArrayList which contains the following two String phrases:

ArrayList<String> words = new ArrayList<String>();
words.add("key1 key2 key3 key4 key5 key6 key7");
words.add("key11 key12 key13 key14 key15 key16 key17");

我想分成5个单词(int desiredListSize = 5;)的块-这将产生以下两个列表:

And I want to split into chunks of 5 words (int desiredListSize = 5;) - this would produce the following two lists:

列表1:

word1 word2 word3 word4 word5
word2 word3 word4 word5 word6
word3 word4 word5 word6 word7

清单2:

word11 word12 word13 word14 word15
word12 word13 word14 word15 word16
word13 word14 word15 word16 word17

上面的每个列表都将添加到Lists of Lists数组中，因此输出将采用以下格式:ArrayList<ArrayList<String>()

Each list above would then be added to List of Lists array so the output would be in format: ArrayList<ArrayList<String>()

到目前为止，以下代码片段解决了大多数问题:

So far the following code fragment solves most of the problem:

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;

public static void splitListIntoWords()
{

    int desiredListSize = 5;
    final ArrayList<String> textWords = new ArrayList<String>(); 
    textWords.add("key1 key2 key3 key4 key5 key6 key7");
    textWords.add("key11 key12 key13 key14 key15 key16 key17");


    final List<List<String>> listOfLists = textWords.stream().flatMap(w -> {

        final String[] wordList = StringX.splitStrIntoWordsRtrnArr(w); // w.split(" ");

        int calculatedListSize = (wordList.length < desiredListSize) ? wordList.length : desiredListSize;

        return  IntStream.range(0, Math.min(wordList.length - (calculatedListSize - 1), wordList.length)).mapToObj(i -> i ).flatMap(i -> Stream.of(
                IntStream.range(i, Math.min(i+desiredListSize, wordList.length)).mapToObj(j -> wordList[j])
                .collect(Collectors.toList())));
    })          .collect(Collectors.toList());


    for (int counter = 0; counter < listOfLists.size(); counter++) {

        System.out.println("LIST: " + counter);


        System.out.println(listOfLists.get(counter).toString());
    }

}

哪个会产生以下输出:

LIST: 0
[key1, key2, key3, key4, key5]
LIST: 1
[key2, key3, key4, key5, key6]
LIST: 2
[key3, key4, key5, key6, key7]
LIST: 3
[key11, key12, key13, key14, key15]
LIST: 4
[key12, key13, key14, key15, key16]
LIST: 5
[key13, key14, key15, key16, key17]

但是理想的输出是:

LIST 0:
key1 key2 key3 key4 key5
key2 key3 key4 key5 key6
key3 key4 key5 key6 key7

LIST 1: 
key11 key12 key13 key14 key15
key12 key13 key14 key15 key16
key13 key14 key15 key16 key17

然后将以上两个列表都添加到listOfLists.

Both lists above should then be added to listOfLists.

请注意，每个列表如何在所需的输出中将对字符串:key1 key2 key3 key4 key5的操作结果存储为单个String(每个单词之间有空格)不作为列表.

Notice how in the desired output each list stores the result of operation on String: key1 key2 key3 key4 key5 as a single String (with a space between each word) NOT as a list.

换句话说，当一个调用listOfLists.get(0);时，应该获得一个包含对words.add("key1 key2 key3 key4 key5 key6 key7");进行操作的结果的列表，而当一个调用listOfLists.get(1);时，应该应当获得对words.add("key11 key12 key13 key14 key15 key16 key17");进行操作的结果.如果原始textWords列表中有两个以上的条目，则listOfLists将包含相应数量的列表.

In other words, when one calls listOfLists.get(0); one should obtain a list that contains the results of operation on words.add("key1 key2 key3 key4 key5 key6 key7"); and when one calls listOfLists.get(1); one should obtain results of operation on words.add("key11 key12 key13 key14 key15 key16 key17"); Of course, if there's more than two entries in original textWords List then listOfLists will contain a corresponding number of lists.

谢谢！

推荐答案

O.S.我现在没有时间完善我的帖子，但是(我认为)原始帖子更好.我明天可能会回来，但我也有一份工作需要做:-)

O.S. I don't have time right now to refine my posting, but here's the better (I think) of the original postings. I may get back tomorrow sometime, but I've got a job that needs doing too :-)

无论如何，这里是:

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;

public class StackOverflow {

    public static void main(final String[] args) {

        final List<String> words = new ArrayList<>();
        words.add("key1 key2 key3 key4 key5 key6 key7");
        words.add("key11 key12 key13 key14 key15 key16 key17");

        final List<List<String>> listOfLists = words.stream().flatMap(w -> {

            final String[] wordList = w.split(" ");

            return  IntStream.range(0, Math.min(  3, wordList.length)).mapToObj(i ->          i ).flatMap(i -> Stream.of(
                    IntStream.range(i, Math.min(i+5, wordList.length)).mapToObj(j -> wordList[j])
                    .collect(Collectors.toList())));
        })          .collect(Collectors.toList());

        listOfLists.forEach(System.out::println);
    }
}

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