Java---正则表达式group的使用

package com.qiyi.regex;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class PatternDemo {

public static void main(String[] args) {
Pattern p = Pattern.compile("chn_(\\d+)_tag_(\\d+)");
Matcher m = p.matcher("chn_250_tag_120");
while(m.find()){
System.out.println(m.group(1));
System.out.println(m.group(2));
}
}

}

[1, 2, 3, 4 ].replaceAll("\\[|]", " ");

//结果： 1, 2, 3, 4