Program -Print all permutations

import java.util.*;
public class permutations{
static ArrayList<String> output = new ArrayList<String>();
public static void main(String[] args){
Scanner sc = new Scanner(System.in);
System.out.println("enter number");
int a = sc.nextInt(); // scanning input from user
String c=a+"";
ArrayList<String> result =  permutations(c,"");    // calling permutate function and receiving the return value
String result1 = "";
int i =0;
for( i =0;i<result.size()-1;i++){
result1+=result.get(i)+","; // printing output in required format
}
result1+=result.get(i);
System.out.println(result1);
}
public static ArrayList<String> permutations(String b,String c){
if(b.length()==0){
output.add(c); // adding output to arraylist
}
else {
for(int i =0;i<b.length();i++){
permutations(b.substring(0,i)+b.substring(i+1,b.length()),c+b.charAt(i));
} // recursively calling the permutate function by
} // making substring of the given string except the i value added to the substrings
return output; // returning arraylist
}

}