我有一个长度为n的单行字符串，我希望将其分成最多3行。每行最多可以有45个字符，之后我想添加一个新行字符（＆＃34; \ n＆＃34;）。第3行最多可以有42个字符，之后我需要包含3个点（...）如果字符串超出该字符串，那么第3行中的总字符数也是如此。
条件是新行字符不应添加到单词的中间。我该如何有效地做到这一点？此操作只是整个程序的一小部分，但会被重复调用。所以我不确定我是否真的应该为效率而烦恼。
我现在正在做的是我首先找出单词之间的空格，然后将其添加到List中。然后我遍历列表并找到3个索引，每个索引代表每行的结束词。所以第一个索引将是最接近45的空间，下一个最接近90的空间，以及最接近135的第三个索引。然后我使用这些索引来分割实际的字符串，并添加＆＃34; \ n＆＃34;和＆＃34; ...＆＃34;分别。这是我的代码：
//maxCharsPerLine will be 45
public String splitString(String input, int maxCharsPerLine){
String output = "";
ArrayList<Integer> spaces = new ArrayList<Integer>();
// Logic to figure out after which word the sentence should be split so that we don't split in middle of a word
for(int index = 0; index < input.length(); index++){
if(input.charAt(index)==' '){
spaces.add(index);
}
}
//add index of last word of string
spaces.add(input.length());
int index1 = 0; int index2 = 0; int index3 = 0;
for(Integer index : spaces){
// find word closest to and less than maxCharsPerLine. This index will be used to find the last word in line1
if(index<=maxCharsPerLine)
index1 = index;
// find word closest to and less than 2*maxCharsPerLine. This index will be used to find the last word in line2
else if(index<=2*maxCharsPerLine)
index2 = index;
// find word closest to and less than 3*maxCharsPerLine, but exclude 3 chars for adding the dots (...). This index will be used to find the last word in line3
else if(index<=(3*maxCharsPerLine)-3)
index3 = index;
}
if(input.length()>maxCharsPerLine){
if(index1 > 0)
output = input.substring(0, index1);
if(index2 > 0)
output += "\n"+input.substring(index1+1, index2);
if(index3 > 0){
output += "\n"+input.substring(index2+1, index3);
if(input.length()>3*maxCharsPerLine)
output += "...";
}
}
//if length of input is < 45, just return the input
else
output = input;
return output;
}
不确定在哪种情况下会失败。有更好的方法吗？
感谢。
答案 0 :(得分：4)
如果不考虑包含3个点，可以使用Apache Commans Lang的WordUtils.wrap方法。
WordUtils.wrap(str, 45)
答案 1 :(得分：1)
<强>代码
public class test3 {
public static void main(String[] args) {
String S = "The condition is that the new line should not be added in the middle of a word. How do I do this efficiently? This operation is just a small part of the entire program, but will be called repeatedly. So I'm not sure if I should actually bother about the efficiency";
String Op = "";
String Op1 = "";
String Op2 = "";
String Op3 = "";
String Temp[] = S.split(" ");
int max_size_1 = 45;
int max_size_2 = 45;
int max_size_3 = 42;
int length = 0;
for (int i = 0; i < Temp.length; i++) {
length = length + Temp[i].length()+1;
if(length <= max_size_1) Op1 = Op1 + Temp[i]+" ";
else if(length <= Op1.length()+max_size_2) Op2 = Op2 +Temp[i]+" ";
else if(length <= Op1.length()+Op2.length()+max_size_3) Op3 = Op3 + Temp[i]+" ";
else {Op3 = Op3 +'\b' + "..."; i =Temp.length ; } //backspace
}
Op = Op1+"\n"+Op2+"\n"+Op3;
System.out.println(Op);
System.out.println(Op1.length()+" "+Op2.length()+" "+Op3.length()+" ");
}}
<强>输出
The condition is that the new line should
not be added in the middle of a word. How do
I do this efficiently? This operation...
42 45 45
答案 2 :(得分：0)
这是另一种解决方案，虽然它可能已损坏并需要进行编辑。
int sizeOfString = input.lenght();
//the maximum lenght of a String
int aPartialStringLenght = 45;
String firstString;
String secondString;
String thirdString;
for(int x = 1; x <= 3; x++){
// looks for the last space before your 45th character
//sets the lenght for the third String to max. 42characters
if(x == 3){
aPartialStringLenght = 42;
}
while(!input.charAt(aPartialStringLenght*x).equals(" ")){
aPartialStringLenght -=1;
}
switch(x){
// gets the substring till your first partialString
case 1: firstString = input.substring(0, aPartialStringlenght);
aPartialStringLenght = 45;
// gets the substring from the end of your first partialString till the end of your second partialString
case 2: secondString = input.substring(firstString.lenght(), aPartialStringLenght + firstString.lenght());
aPartialStringLenght = 45;
// gets the substring from the end of your second partialString till till the end of your third partialString + "..."
case 3 thirdString = input.substring(firstString.lenght()+secondString.lenght(), aPartialStringLenght + firstString.lenght()+ secondString.lenght() )+"..."
aPartialStringLenght = 45;
}
}
答案 3 :(得分：0)
基于surya回答
public class test3 {
public static void main(String[] args) {
String S = "The condition is that the new line should not be added in the middle of a word. How do I do this efficiently? This operation is just a small part of the entire program, but will be called repeatedly. So I'm not sure if I should actually bother about the efficiency";
String F = WordUtils.wrap(S, 45);
String[] F1 = F.split(System.lineSeparator());
System.out.println(F1[0]);
System.out.println(F1[1]);
F1[2] = F1[2] +'\b'+'\b'+'\b'+"...";
System.out.println(F1[2]);
}
}
输出
The condition is that the new line should not
be added in the middle of a word. How do I do
this efficiently? This operation is jus...
答案 4 :(得分：0)
我的建议效率很高，因为：
它也很灵活，因为所有涉及的数据都是作为参数接收的：
public final class LinesSplitter
{
private LinesSplitter(){}
private static final char NL='\n';
public static String splitInLines(String text, int maxLineLength, int maxLines, String lastLineSuffix)
{
StringBuilder output=new StringBuilder((1 + maxLineLength) * maxLines);
int p=0;
int startOfLine=0;
int lastBlank=0;
int lastNonBlank=0;
int len=text.length();
String neededSuffix=text.length() > maxLineLength * maxLines
? lastLineSuffix
: "";
int lines=0;
while (lines < maxLines && p < len)
{
char c=text.charAt(p);
if (Character.isWhitespace(c))
{
lastBlank=p;
lastNonBlank=1 + p;
}
else if (p < len)
{
int maxLengthForCurrentLine=getMaxLength(maxLineLength, maxLines, 1 + lines, neededSuffix);
if (p - startOfLine == maxLengthForCurrentLine)
{
output.append(text, startOfLine, lastBlank);
String suffix=getSuffix(maxLineLength, maxLines, 1 + lines, neededSuffix);
if (!suffix.isEmpty())
{
output.append(suffix);
}
else
{
output.append(NL);
}
lines++;
startOfLine=lastNonBlank;
}
}
p++;
}
if (lines < maxLines && p - startOfLine > 0)
{
output.append(text, startOfLine, len);
}
return output.toString();
}
private final static int getMaxLength(int maxLineLength, int maxLines, int currentLine, String lastLineSuffix)
{
return currentLine == maxLines
? maxLineLength - lastLineSuffix.length()
: maxLineLength;
}
private final static String getSuffix(int maxLineLength, int maxLines, int currentLine, String lastLineSuffix)
{
return currentLine == maxLines
? lastLineSuffix
: "";
}
}
唯一可能的缺点是它不支持几个相邻的空白。