Error ! Note: Main.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details

#1

import java.util.*;
public class Main {
public static ArrayList getSS(String str){
//baseCase
if(str.length() == 0 ){
ArrayList bResult = new ArrayList();
bResult.add(" ");
return bResult;
}
//action
char cc = str.charAt(0);
String ros = str.substring(1);
ArrayList result = new ArrayList();
ArrayList rResult = getSS(ros);
for(int i = 0 ; i < rResult.size() ; i++){
result.add(rResult.get(i));
result.add(cc + rResult.get(i));
}
return result;

}

public static void display(ArrayList<String> arrL){
    for(int i = 0 ; i < arrL.size() ; i++){
        System.out.println(arrL.get(i));
    }
}
public static void main(String args[]) {
    Scanner scn = new Scanner(System.in);
    int t = scn.nextInt();
    for(int i = 0 ; i < t ; i++){

        String str = scn.next();
        if(str.length() > 1 && str.length() < 20){
            display( getSS(str));

            System.out.println();

       }
    }
}

}

#2

mention the type in arraylist everywhere
as
ArrayList<String> result = new ArrayList<>();