字符串变形：比如"Hello World"变形后就变成了"wORLD hELLO", list逆序Collections.reverse(strList)

 

 

import java.util.*;

public class Solution {

    public String trans(String s, int n) {

        String[] strArray = s.split(" ");

        List<String> strList = Arrays.asList(strArray);

        Collections.reverse(strList);

        StringBuffer sb = new StringBuffer();

        for(int i=0; i<strList.size(); i++){

            char[] tmp = strList.get(i).toCharArray();

            for(int j=0; j<tmp.length; j++){

                if(Character.isLowerCase(tmp[j])){

                   sb.append(Character.toUpperCase(tmp[j]));

                }

                if(Character.isUpperCase(tmp[j])){

                    sb.append(Character.toLowerCase(tmp[j]));

                }

            }

            if(i!=strList.size()-1){

                sb.append(" ");

            }            

        }

        if(s.startsWith(" ")){

            sb.append(" ");

            return sb.toString();

        }

        if(s.endsWith(" ")){

            return " "+sb.toString();

        }

        return sb.toString();

    }

}