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:
" + str + "
Token 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.");
  }
}