大字符串在java中分割成具有最大長度的行

Question

String input = "THESE TERMS AND CONDITIONS OF SERVICE (the Terms) ARE A LEGAL AND BINDING AGREEMENT BETWEEN YOU AND NATIONAL GEOGRAPHIC governing your use of this site, www.nationalgeographic.com, which includes but is not limited to products, software and services offered by way of the website such as the Video Player, Uploader, and other applications that link to these Terms (the Site). Please review the Terms fully before you continue to use the Site. By using the Site, you agree to be bound by the Terms. You shall also be subject to any additional terms posted with respect to individual sections of the Site. Please review our Privacy Policy, which also governs your use of the Site, to understand our practices. If you do not agree, please discontinue using the Site. National Geographic reserves the right to change the Terms at any time without prior notice. Your continued access or use of the Site after such changes indicates your acceptance of the Terms as modified. It is your responsibility to review the Terms regularly. The Terms were last updated on 18 July 2011.";

//text copied from http://www.nationalgeographic.com/community/terms/

我想將這個大字符串拆分成行，並且每行中的行不應超過MAX_LINE_LENGTH個字符。

到目前為止我嘗試了什么

int MAX_LINE_LENGTH = 20;    
System.out.print(Arrays.toString(input.split("(?<=\\G.{MAX_LINE_LENGTH})")));
//maximum length of line 20 characters

輸出：

[THESE TERMS AND COND, ITIONS OF SERVICE (t, he Terms) ARE A LEGA, L AND B ...

它導致文字破裂 。 我不想要這個。 而不是我想得到這樣的輸出：

[THESE TERMS AND , CONDITIONS OF , SERVICE (the Terms) , ARE A LEGAL AND B ...

還添加了一個條件：如果字長大於MAX_LINE_LENGTH，那么該單詞應該被拆分。

解決方案應該沒有外部罐子的幫助。

Answer 1

只需逐字遍歷字符串，並在單詞超出限制時中斷。

public String addLinebreaks(String input, int maxLineLength) {
    StringTokenizer tok = new StringTokenizer(input, " ");
    StringBuilder output = new StringBuilder(input.length());
    int lineLen = 0;
    while (tok.hasMoreTokens()) {
        String word = tok.nextToken();

        if (lineLen + word.length() > maxLineLength) {
            output.append("\n");
            lineLen = 0;
        }
        output.append(word);
        lineLen += word.length();
    }
    return output.toString();
}

我只是徒手打字，你可能需要推動並刺激一下才能編譯。

錯誤：如果輸入中的單詞長於maxLineLength ，它將被附加到當前行而不是它自己的太長行。 我假設您的行長度類似於80或120個字符，在這種情況下，這不太可能是一個問題。

Answer 2

最佳：使用Apache Commons Lang：

org.apache.commons.lang.WordUtils

/**
 * <p>Wraps a single line of text, identifying words by <code>' '</code>.</p>
 * 
 * <p>New lines will be separated by the system property line separator.
 * Very long words, such as URLs will <i>not</i> be wrapped.</p>
 * 
 * <p>Leading spaces on a new line are stripped.
 * Trailing spaces are not stripped.</p>
 *
 * <pre>
 * WordUtils.wrap(null, *) = null
 * WordUtils.wrap("", *) = ""
 * </pre>
 *
 * @param str  the String to be word wrapped, may be null
 * @param wrapLength  the column to wrap the words at, less than 1 is treated as 1
 * @return a line with newlines inserted, <code>null</code> if null input
 */
public static String wrap(String str, int wrapLength) {
    return wrap(str, wrapLength, null, false);
}

Answer 3

感謝Barend Garvelink的回答。 我修改了上面的代碼來修復Bug：“如果輸入中的單詞長於maxCharInLine”

public String[] splitIntoLine(String input, int maxCharInLine){

    StringTokenizer tok = new StringTokenizer(input, " ");
    StringBuilder output = new StringBuilder(input.length());
    int lineLen = 0;
    while (tok.hasMoreTokens()) {
        String word = tok.nextToken();

        while(word.length() > maxCharInLine){
            output.append(word.substring(0, maxCharInLine-lineLen) + "\n");
            word = word.substring(maxCharInLine-lineLen);
            lineLen = 0;
        }

        if (lineLen + word.length() > maxCharInLine) {
            output.append("\n");
            lineLen = 0;
        }
        output.append(word + " ");

        lineLen += word.length() + 1;
    }
    // output.split();
    // return output.toString();
    return output.toString().split("\n");
}

Answer 4

您可以使用Apache Commans Lang的WordUtils.wrap方法

 import java.util.*;
 import org.apache.commons.lang3.text.WordUtils;
 public class test3 {


public static void main(String[] args) {

    String S = "THESE TERMS AND CONDITIONS OF SERVICE (the Terms) ARE A LEGAL AND BINDING AGREEMENT BETWEEN YOU AND NATIONAL GEOGRAPHIC governing your use of this site, www.nationalgeographic.com, which includes but is not limited to products, software and services offered by way of the website such as the Video Player, Uploader, and other applications that link to these Terms (the Site). Please review the Terms fully before you continue to use the Site. By using the Site, you agree to be bound by the Terms. You shall also be subject to any additional terms posted with respect to individual sections of the Site. Please review our Privacy Policy, which also governs your use of the Site, to understand our practices. If you do not agree, please discontinue using the Site. National Geographic reserves the right to change the Terms at any time without prior notice. Your continued access or use of the Site after such changes indicates your acceptance of the Terms as modified. It is your responsibility to review the Terms regularly. The Terms were last updated on 18 July 2011.";
    String F = WordUtils.wrap(S, 20);
    String[] F1 =  F.split(System.lineSeparator());
    System.out.println(Arrays.toString(F1));

}}

產量

   [THESE TERMS AND, CONDITIONS OF, SERVICE (the Terms), ARE A LEGAL AND, BINDING AGREEMENT, BETWEEN YOU AND, NATIONAL GEOGRAPHIC, governing your use, of this site,, www.nationalgeographic.com,, which includes but, is not limited to, products, software, and services offered, by way of the, website such as the, Video Player,, Uploader, and other, applications that, link to these Terms, (the Site). Please, review the Terms, fully before you, continue to use the, Site. By using the, Site, you agree to, be bound by the, Terms. You shall, also be subject to, any additional terms, posted with respect, to individual, sections of the, Site. Please review, our Privacy Policy,, which also governs, your use of the, Site, to understand, our practices. If, you do not agree,, please discontinue, using the Site., National Geographic, reserves the right, to change the Terms, at any time without, prior notice. Your, continued access or, use of the Site, after such changes, indicates your, acceptance of the, Terms as modified., It is your, responsibility to, review the Terms, regularly. The Terms, were last updated on, 18 July 2011.]

Answer 5

從@Barend的建議開始，以下是我的最終版本，稍作修改：

private static final char NEWLINE = '\n';
private static final String SPACE_SEPARATOR = " ";
//if text has \n, \r or \t symbols it's better to split by \s+
private static final String SPLIT_REGEXP= "\\s+";

public static String breakLines(String input, int maxLineLength) {
    String[] tokens = input.split(SPLIT_REGEXP);
    StringBuilder output = new StringBuilder(input.length());
    int lineLen = 0;
    for (int i = 0; i < tokens.length; i++) {
        String word = tokens[i];

        if (lineLen + (SPACE_SEPARATOR + word).length() > maxLineLength) {
            if (i > 0) {
                output.append(NEWLINE);
            }
            lineLen = 0;
        }
        if (i < tokens.length - 1 && (lineLen + (word + SPACE_SEPARATOR).length() + tokens[i + 1].length() <=
                maxLineLength)) {
            word += SPACE_SEPARATOR;
        }
        output.append(word);
        lineLen += word.length();
    }
    return output.toString();
}

System.out.println(breakLines("THESE TERMS AND CONDITIONS OF SERVICE (the Terms) ARE A     LEGAL AND BINDING " +
                "AGREEMENT BETWEEN YOU AND NATIONAL GEOGRAPHIC governing     your use of this site, " +
            "www.nationalgeographic.com, which includes but is not limited to products, " +
            "software and services offered by way of the website such as the Video Player.", 20));

產出：

THESE TERMS AND
CONDITIONS OF
SERVICE (the Terms)
ARE A LEGAL AND
BINDING AGREEMENT
BETWEEN YOU AND
NATIONAL GEOGRAPHIC
governing your use
of this site,
www.nationalgeographic.com,
which includes but
is not limited to
products, software
and services 
offered by way of
the website such as
the Video Player.

Answer 6

我最近編寫了一些方法來執行此操作，如果其中一行中沒有空格字符，則在求助於中間詞拆分之前選擇拆分其他非字母數字字符。

以下是我的結果：

（使用我在這里發布的lastIndexOfRegex()方法。）

/**
 * Indicates that a String search operation yielded no results.
 */
public static final int NOT_FOUND = -1;



/**
 * Version of lastIndexOf that uses regular expressions for searching.
 * By Tomer Godinger.
 * 
 * @param str String in which to search for the pattern.
 * @param toFind Pattern to locate.
 * @return The index of the requested pattern, if found; NOT_FOUND (-1) otherwise.
 */
public static int lastIndexOfRegex(String str, String toFind)
{
    Pattern pattern = Pattern.compile(toFind);
    Matcher matcher = pattern.matcher(str);

    // Default to the NOT_FOUND constant
    int lastIndex = NOT_FOUND;

    // Search for the given pattern
    while (matcher.find())
    {
        lastIndex = matcher.start();
    }

    return lastIndex;
}

/**
 * Finds the last index of the given regular expression pattern in the given string,
 * starting from the given index (and conceptually going backwards).
 * By Tomer Godinger.
 * 
 * @param str String in which to search for the pattern.
 * @param toFind Pattern to locate.
 * @param fromIndex Maximum allowed index.
 * @return The index of the requested pattern, if found; NOT_FOUND (-1) otherwise.
 */
public static int lastIndexOfRegex(String str, String toFind, int fromIndex)
{
    // Limit the search by searching on a suitable substring
    return lastIndexOfRegex(str.substring(0, fromIndex), toFind);
}

/**
 * Breaks the given string into lines as best possible, each of which no longer than
 * <code>maxLength</code> characters.
 * By Tomer Godinger.
 * 
 * @param str The string to break into lines.
 * @param maxLength Maximum length of each line.
 * @param newLineString The string to use for line breaking.
 * @return The resulting multi-line string.
 */
public static String breakStringToLines(String str, int maxLength, String newLineString)
{
    StringBuilder result = new StringBuilder();
    while (str.length() > maxLength)
    {
        // Attempt to break on whitespace first,
        int breakingIndex = lastIndexOfRegex(str, "\\s", maxLength);

        // Then on other non-alphanumeric characters,
        if (breakingIndex == NOT_FOUND) breakingIndex = lastIndexOfRegex(str, "[^a-zA-Z0-9]", maxLength);

        // And if all else fails, break in the middle of the word
        if (breakingIndex == NOT_FOUND) breakingIndex = maxLength;

        // Append each prepared line to the builder
        result.append(str.substring(0, breakingIndex + 1));
        result.append(newLineString);

        // And start the next line
        str = str.substring(breakingIndex + 1);
    }

    // Check if there are any residual characters left
    if (str.length() > 0)
    {
        result.append(str);
    }

    // Return the resulting string
    return result.toString();
}

Answer 7

我的版本（之前沒有用）

public static List<String> breakSentenceSmart(String text, int maxWidth) {

    StringTokenizer stringTokenizer = new StringTokenizer(text, " ");
    List<String> lines = new ArrayList<String>();
    StringBuilder currLine = new StringBuilder();
    while (stringTokenizer.hasMoreTokens()) {
        String word = stringTokenizer.nextToken();

        boolean wordPut=false;
        while (!wordPut) {
            if(currLine.length()+word.length()==maxWidth) { //exactly fits -> dont add the space
                currLine.append(word);
                wordPut=true;
            }
            else if(currLine.length()+word.length()<=maxWidth) { //whole word can be put
                if(stringTokenizer.hasMoreTokens()) {
                    currLine.append(word + " ");
                }else{
                    currLine.append(word);
                }
                wordPut=true;
            }else{
                if(word.length()>maxWidth) {
                    int lineLengthLeft = maxWidth - currLine.length();
                    String firstWordPart = word.substring(0, lineLengthLeft);
                    currLine.append(firstWordPart);
                    //lines.add(currLine.toString());
                    word = word.substring(lineLengthLeft);
                    //currLine = new StringBuilder();
                }
                lines.add(currLine.toString());
                currLine = new StringBuilder();
            }

        }
        //
    }
    if(currLine.length()>0) { //add whats left
        lines.add(currLine.toString());
    }
    return lines;
}

Answer 8

從Java 8開始，您也可以使用Streams來解決此類問題。

下面你可以找到一個使用.collect（）方法利用Reduction的完整示例

我認為這個應該比其他非第三方解決方案更短。

private static String multiLine(String longString, String splitter, int maxLength) {
    return Arrays.stream(longString.split(splitter))
            .collect(
                ArrayList<String>::new,     
                (l, s) -> {
                    Function<ArrayList<String>, Integer> id = list -> list.size() - 1;
                    if(l.size() == 0 || (l.get(id.apply(l)).length() != 0 && l.get(id.apply(l)).length() + s.length() >= maxLength)) l.add("");
                    l.set(id.apply(l), l.get(id.apply(l)) + (l.get(id.apply(l)).length() == 0 ? "" : splitter) + s);
                },
                (l1, l2) -> l1.addAll(l2))
            .stream().reduce((s1, s2) -> s1 + "\n" + s2).get();
}

public static void main(String[] args) {
    String longString = "THESE TERMS AND CONDITIONS OF SERVICE (the Terms) ARE A LEGAL AND BINDING AGREEMENT BETWEEN YOU AND NATIONAL GEOGRAPHIC governing your use of this site, www.nationalgeographic.com, which includes but is not limited to products, software and services offered by way of the website such as the Video Player, Uploader, and other applications that link to these Terms (the Site). Please review the Terms fully before you continue to use the Site. By using the Site, you agree to be bound by the Terms. You shall also be subject to any additional terms posted with respect to individual sections of the Site. Please review our Privacy Policy, which also governs your use of the Site, to understand our practices. If you do not agree, please discontinue using the Site. National Geographic reserves the right to change the Terms at any time without prior notice. Your continued access or use of the Site after such changes indicates your acceptance of the Terms as modified. It is your responsibility to review the Terms regularly. The Terms were last updated on 18 July 2011.";
    String SPLITTER = " ";
    int MAX_LENGTH = 20;
    System.out.println(multiLine(longString, SPLITTER, MAX_LENGTH));
}