Java基础之一组有用的类——为标记定义自己的模式（ScanString)

控制台程序。

Scanner类提供了一种方式，用来指定如何识别标记。这需要使用next()方法的两个重载版本。其中的一个版本接受Pattern类型的参数。另一个版本接受String类型的参数，用来指定标识标记的正则表达式。在这两个版本中，标记都返回为String类型。

 import java.util.Scanner;
 import java.util.regex.Pattern;

 public class ScanString {
   public static void main(String[] args) {
     String str = "Smith , where Jones had had 'had', had had 'had had'.";
     String regex = "had";
     System.out.println("String is:\n" + str + "\nToken sought is: " + regex);

     Pattern had = Pattern.compile(regex);
     Scanner strScan = new Scanner(str);
 //    strScan.useDelimiter("[^\\w*]");
     int hadCount = 0;
     while(strScan.hasNext()) {
       if(strScan.hasNext(had)) {
         ++hadCount;
         System.out.println("Token found!: " + strScan.next(had));
       } else {
         System.out.println("Token is    : " + strScan.next());
       }
     }
     System.out.println(hadCount + " instances of \"" + regex +  "\" were found.");
   }
 }