面试题05. 替换空格

请实现一个函数，把字符串 s 中的每个空格替换成"%20"。

示例 1：

输入：s = “We are happy.”
输出：“We%20are%20happy.”

解题代码

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

/**
 * @Auther: truedei
 * @Date: 2020 /20-5-6 22:46
 * @Description:
 */
public class TestA {

    static public String replaceSpace(String s) {
        //1693648纳秒
        return s.replaceAll("[ ]", "%20");

        //1355205纳秒
        return s.replace(" ","%20");


        //636976纳秒
        StringBuilder s1 = new StringBuilder();
        for (int i = 0; i < s.length(); i++) {
            if(s.charAt(i)==(char)' '){
                s1.append("%20");
            }else {
                s1.append(s.charAt(i));
            }
        }
        return s1.toString();

        //594273纳秒
        String s1="";
        for (int i = 0; i < s.length(); i++) {
            if(s.charAt(i)==(char)' '){
                s1=s1+"%20";
            }else {
                s1=s1+s.charAt(i);
            }
        }
        return s1;
    }

}