Problem solving hackererank

 import java.io.*;

import java.math.*;

import java.security.*;

import java.text.*;

import java.util.*;

import java.util.concurrent.*;

import java.util.function.*;

import java.util.regex.*;

import java.util.stream.*;

import static java.util.stream.Collectors.joining;

import static java.util.stream.Collectors.toList;

class Result {

/*

* Complete the 'decryptPassword' function below.

*

* The function is expected to return a STRING.

* The function accepts STRING s as parameter.

*/

public static String decryptPassword(String s) {

// Write your code here

if (s.matches("^[a-zA-Z0-9]*$") && s.contains("*")){

List<String> strList = new LinkedList<String>();

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

if(

Character.isLowerCase(strList.get(i).charAt(0)) &&

Character.isUpperCase(strList.get(i+1).charAt(0))

){

String a = strList.get(i);

String b = strList.get(i+1);

strList.set(i, b);

strList.set(i+1, a);

strList.add(i+2, "*");

}

}

}

return "sds";

}

}

public class Solution {

public static void main(String[] args) throws IOException {

BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));

BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

String s = bufferedReader.readLine();

String result = Result.decryptPassword(s);

bufferedWriter.write(result);

bufferedWriter.newLine();

bufferedReader.close();

bufferedWriter.close();

}

}