X??

描述 (Description)

Relunsant Quantifier [X??]匹配存在一次或根本不存在的X.

例子 (Example)

以下示例显示了不情愿量词的用法。

package cn.xnip;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class ReluctantQuantifierDemo {
   private static final String REGEX = "T??";
   private static final String INPUT = "abcdTatW";
   public static void main(String[] args) {
      // create a pattern
      Pattern  pattern = Pattern.compile(REGEX);
      // get a matcher object
      Matcher matcher = pattern.matcher(INPUT); 
      while(matcher.find()) {
         //Prints the start index of the match.
         System.out.println("Match String start(): "+matcher.start());
      }
   }
}

让我们编译并运行上面的程序，这将产生以下结果 -

Match String start(): 0
Match String start(): 1
Match String start(): 2
Match String start(): 3
Match String start(): 4
Match String start(): 5
Match String start(): 6
Match String start(): 7
Match String start(): 8