JAVA中正则表达式常用的四个方法

　　JAVA中正则表达式处理字符串的四个常用方法：匹配、分割、替换、截取。其跟字符串的常用函数相似，但是使用正则表达式会更简单、更加简洁。下面是具体的例子：

 public class TestRegex {

     public static void main(String[] args) {
         String str = "";
         String regex = "";

         // 匹配
         regex = "[1-9][a-z]";
         getMatches(str, regex);

         // 分割
         str = "1a<a>:abc123:</a>";
         regex = ":";
         getSpilt(str, regex);

         // 替换
         str = "1223334444aaabbc";
         String oldChar = "(.)\\1+";
         regex = "$1";
         getReplace(str, oldChar, regex);

         // 截取
         str = "<title>test string</title><a>url</a><content>abc123</content>";
         regex = "<a>(.*)</a>";
         getSubstring(str, regex);

     }

     public static void getMatches(String str, String regex) {
         System.out.println(str.matches(regex));
     }

     public static void getSpilt(String str, String regex) {
         String[] array = str.split(regex);
         for (String t : array) {
             System.out.println(t);
         }
     }

     public static void getReplace(String str, String oldChar, String regex) {
         System.out.println(str.replaceAll(oldChar, regex));
     }

     public static void getSubstring(String str, String regex) {
         Pattern p = Pattern.compile(regex);
         Matcher m = p.matcher(str);
         if (m.find()) {
             System.out.println(m.group(1));
         }
     }
 }