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));
        }
    }
}