Cadena grande dividida en líneas con longitud máxima en java

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/ 

Quiero dividir esta cadena grande en líneas y las líneas no deben contener más de MAX_LINE_LENGTH caracteres en cada línea.

lo que he intentado hasta ahora

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

Salida:

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

Causa ruptura de palabras. No quiero esto En lugar de quiero obtener una salida como ésta:

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

una condición más añadido: Si una longitud de palabra es mayor que MAX_LINE_LENGTH entonces la palabra debe llegar dividida.

Y la solución debe ser sin ayuda de jarras externas.

Answer 1

Simplemente itere a través de la cadena palabra por palabra y rompa cada vez que una palabra pase el límite.

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(); 
} 

Acabo de escribir eso a mano alzada, puede que tenga que presionar y pinchar un poco para que se compile.

Error: si una palabra en la entrada es más larga que maxLineLength se agregará a la línea actual en lugar de en una línea demasiado larga. Supongo que la longitud de su línea es algo así como 80 o 120 caracteres, en cuyo caso es poco probable que sea un problema.

Answer 2

Recientemente he escrito algunos métodos para hacer esto que, si no hay caracteres en blanco en una de las líneas, opta por dividir en otros caracteres no alfanuméricos antes de recurrir a una división de palabra intermedia.

Aquí es cómo resultó para mí:

(utiliza los métodos que he publicado lastIndexOfRegex()here.)

/** 
* 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 3

Gracias Barend Garvelink por su respuesta. He modificado el código anterior para corregir el error : "si una palabra en la entrada es más larga que 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

A partir de la sugerencia @Barend 's, siguiendo es mi versión final, con modificaciones menores:

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)); 

Salidas:

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 5

mejor: utilizar 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 6

Puede utilizar WordUtils.Método de envoltura de Apache Commans Lang

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)); 

}} 

salida

[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 7

Mi versión (La anterior no funcionaban)

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

Desde Java 8 también se puede utilizar corrientes a abordar tales problemas.

Después se puede encontrar un ejemplo completo que utiliza Reduction using the .collect() method

Creo que éste debe ser más corta que otras soluciones no 3 ª parte.

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)); 
}