package cn.netkiller;

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

public class Test {

    public static void main(String[] args) {

        Pattern pattern = Pattern.compile("www|netkiller");
        Matcher matcher = pattern.matcher("https://www.netkiller.cn/linux/index.html");
        if (matcher.find()) {
            String s = matcher.replaceFirst("api"); //替换后的字符串
            System.out.println(s);
        }

    }
}			
			
		

			
package cn.netkiller;

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

public class Test {


    public static void main(String[] args) {

        Pattern pattern = Pattern.compile("www|netkiller");
        Matcher matcher = pattern.matcher("https://www.netkiller.cn/linux/index.html");
        if (matcher.find()) {
            String s = matcher.replaceAll("test"); //替换后的字符串
            System.out.println(s);
            // 输出结果：https://test.test.cn/linux/index.html
        }

    }
}
			
		

			
"aab".replaceAll("a{1}", "x"); //xxb
"aba".replaceAll("a{1}", "x"); //xbx

"abaaabaaaba".replaceAll("a{2}", "x");  //abxabxaba
"abaabaaaaba".replaceAll("a{2}", "x"); //abxbxxba