[英]Java: splitting a comma-separated string but ignoring commas in parentheses
我有一个这样的字符串:
one,two,3,(4,five),six,(seven),(8,9,ten),eleven,(twelve,13,14,fifteen)
上面的字符串应该分成:
one
two
3
(4,five)
six
(seven)
(8,9,ten)
eleven
(twelve,13,14,fifteen)
我认为最简单的解决方案是逐字符处理输入字符串:
public static List<String> split(String input) {
int nParens = 0;
int start = 0;
List<String> result = new ArrayList<>();
for(int i=0; i<input.length(); i++) {
switch(input.charAt(i)) {
case ',':
if(nParens == 0) {
result.add(input.substring(start, i));
start = i+1;
}
break;
case '(':
nParens++;
break;
case ')':
nParens--;
if(nParens < 0)
throw new IllegalArgumentException("Unbalanced parenthesis at offset #"+i);
break;
}
}
if(nParens > 0)
throw new IllegalArgumentException("Missing closing parenthesis");
result.add(input.substring(start));
return result;
}
例子:
split("one,two,3,(4,five),six,(seven),(8,9,ten),eleven,(twelve,13,14,fifteen)") ->
[one, two, 3, (4,five), six, (seven), (8,9,ten), eleven, (twelve,13,14,fifteen)]
作为免费奖励,如果需要,此解决方案还会计算嵌套括号:
split("one,two,3,(4,(five,six),seven),eight") ->
[one, two, 3, (4,(five,six),seven), eight]
它还检查括号是否平衡(每个左括号都有相应的右括号)。
有一个相对简单的单行解决方案:
String[] parts = input.split(",(?![^()]*\\))");
干得好... :)
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;
/**
*
* @author S1LENT W@RRIOR
*/
public class Tokenizer {
public static void main(String... args) {
List<String> tokens = new ArrayList(); // List to store tokens
String string = "one,two,3,(4,five),six,(seven),(8,9,ten),eleven,(twelve,13,14,fifteen)"; // input string
StringTokenizer tokenizer = new StringTokenizer(string, "(),", true); // tokenize your string on the basis of these parentheses
while (tokenizer.hasMoreElements()) { // iterate over tokens
String aToken = (String) tokenizer.nextElement(); // get a token
if (aToken.equals("(")) { // if token is the begining of a parenthisis
StringBuilder sb = new StringBuilder(aToken);
String nextToken = (String) tokenizer.nextElement(); // get next token
while (!nextToken.equals(")")) { // iterate over next tokens untill you find the ending bracket
sb.append(nextToken);
nextToken = (String) tokenizer.nextElement();
}
sb.append(")");
tokens.add(sb.toString()); // add to tokens list
} else if(aToken.equals(",")) { // need this to avoid adding commas
// do nothing
} else {
tokens.add(aToken); // add to tokens list
}
}
for(String aToken: tokens) { // print all tokens
System.out.println(aToken);
}
}
}
使用正则表达式。
String s = "one,two,3,(4,five),six,(seven),(8,9,ten),eleven,(twelve,13,14,fifteen)";
Matcher m = Pattern.compile("[^,()]+|\\([^)]*\\)").matcher(s);
while (m.find())
System.out.println(m.group());
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