Java中的Matcher pattern()方法与示例
该java.util.regex.Matcher中的类代表一个引擎，进行各种匹配操作。该类没有构造函数，可以使用matches()类java.util.regex.Pattern的方法创建/获取该类的对象。
此类（Matcher）的pattern()方法获取并返回由当前Matcher解释的Pattern（对象）。
例子1
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class PatternExample {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter your date of birth (MM/DD/YYY)");
String date = sc.next();
String regex = "^(1[0-2]|0[1-9])/(3[01]|[12][0-9]|0[1-9])/[0-9]{4}$";
//创建一个模式对象
Pattern pattern = Pattern.compile(regex);
//创建一个Matcher对象
Matcher matcher = pattern.matcher(date);
//验证日期
if(matcher.matches())
System.out.println("Date is valid");
else
System.out.println("Date is not valid");
//检索使用的模式
Pattern p = matcher.pattern();
System.out.println("Pattern used to match the given date: \n"+p);
}
}输出结果
Enter your date of birth
01/21/2019
Date is valid
Pattern used to match the given date:
^(1[0-2]|0[1-9])/(3[01]|[12][0-9]|0[1-9])/[0-9]{4}$例子2
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class PatternExample {
public static void main(String args[]) {
//从用户读取字符串
System.out.println("Enter a String");
Scanner sc = new Scanner(System.in);
String input = sc.next();
//正则表达式匹配以数字开头的单词
String regex = "^[0-9].*$";
//编译正则表达式
Pattern pattern = Pattern.compile(regex);
//检索匹配器对象
Matcher matcher = pattern.matcher(input);
Pattern p = matcher.pattern();
System.out.println("Pattern used to match the given input string: "+p);
//验证是否发生匹配
if(matcher.matches())
System.out.println("First character is a digit");
else
System.out.println("First character is not a digit");
}
}输出结果
Enter a String 2sample Pattern used to match the given input string: ^[0-9].*$ First character is a digit