我想在字符串中搜索特定模式。
正则表达式类是否提供模式在字符串中的位置(字符串中的索引)?
模式的出现次数可能超过1。
有实际的例子吗?
Answers:
使用Matcher:
public static void printMatches(String text, String regex) {
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(text);
// Check all occurrences
while (matcher.find()) {
System.out.print("Start index: " + matcher.start());
System.out.print(" End index: " + matcher.end());
System.out.println(" Found: " + matcher.group());
}
}
Jean Logeart的特别版答案
public static int[] regExIndex(String pattern, String text, Integer fromIndex){
Matcher matcher = Pattern.compile(pattern).matcher(text);
if ( ( fromIndex != null && matcher.find(fromIndex) ) || matcher.find()) {
return new int[]{matcher.start(), matcher.end()};
}
return new int[]{-1, -1};
}
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class RegexMatches
{
public static void main( String args[] ){
// String to be scanned to find the pattern.
String line = "This order was places for QT3000! OK?";
String pattern = "(.*)(\\d+)(.*)";
// Create a Pattern object
Pattern r = Pattern.compile(pattern);
// Now create matcher object.
Matcher m = r.matcher(line);
if (m.find( )) {
System.out.println("Found value: " + m.group(0) );
System.out.println("Found value: " + m.group(1) );
System.out.println("Found value: " + m.group(2) );
} else {
System.out.println("NO MATCH");
}
}
}
结果
Found value: This order was places for QT3000! OK?
Found value: This order was places for QT300
Found value: 0
(.*)
最初消耗了整个字符串,然后回退了足够远的距离以(\d+)
匹配一个数字,然后第二个(.*)
消耗了剩下的任何东西。我会说这不是特别有用的结果。哦,您忘group(3)
了结果了。