Java 创建正则表达式匹配数组

Question

在Java中，我试图将所有正则表达式匹配项返回到数组，但是似乎您只能检查模式是否匹配某些内容（布尔值）。

如何使用正则表达式匹配在给定字符串中形成所有与正则表达式匹配的字符串数组？

Answer 1

（如果你可以假设Java> = 9，则4castle的答案比下面的要好）

你需要创建一个匹配器，并使用它来迭代查找匹配项。

 import java.util.regex.Matcher;
 import java.util.regex.Pattern;

 ...

 List<String> allMatches = new ArrayList<String>();
 Matcher m = Pattern.compile("your regular expression here")
     .matcher(yourStringHere);
 while (m.find()) {
   allMatches.add(m.group());
 }

之后，allMatches包含匹配项，allMatches.toArray(new String[0])如果你确实需要一个数组，则可以使用它来获取一个数组。

MatchResult由于Matcher.toMatchResult()返回了当前组状态的快照，因此你还可以编写辅助函数来循环匹配。

例如，你可以编写一个惰性迭代器来完成

for (MatchResult match : allMatches(pattern, input)) {
  // Use match, and maybe break without doing the work to find all possible matches.
}

通过做这样的事情：

public static Iterable<MatchResult> allMatches(
      final Pattern p, final CharSequence input) {
  return new Iterable<MatchResult>() {
    public Iterator<MatchResult> iterator() {
      return new Iterator<MatchResult>() {
        // Use a matcher internally.
        final Matcher matcher = p.matcher(input);
        // Keep a match around that supports any interleaving of hasNext/next calls.
        MatchResult pending;

        public boolean hasNext() {
          // Lazily fill pending, and avoid calling find() multiple times if the
          // clients call hasNext() repeatedly before sampling via next().
          if (pending == null && matcher.find()) {
            pending = matcher.toMatchResult();
          }
          return pending != null;
        }

        public MatchResult next() {
          // Fill pending if necessary (as when clients call next() without
          // checking hasNext()), throw if not possible.
          if (!hasNext()) { throw new NoSuchElementException(); }
          // Consume pending so next call to hasNext() does a find().
          MatchResult next = pending;
          pending = null;
          return next;
        }

        /** Required to satisfy the interface, but unsupported. */
        public void remove() { throw new UnsupportedOperationException(); }
      };
    }
  };
}

有了这个，

for (MatchResult match : allMatches(Pattern.compile("[abc]"), "abracadabra")) {
  System.out.println(match.group() + " at " + match.start());
}

产量

a at 0
b at 1
a at 3
c at 4
a at 5
a at 7
b at 8
a at 10