print all possible strings for any phone no based on a phone pad

phoneNum2String

private final static Map<Integer, char[]> store = new HashMap<>();
static {  
store.put(1, new char[]{'1'});
store.put(2, new char[]{'A', 'B', 'C'});
store.put(3, new char[]{'D', 'E', 'F'});  
store.put(4, new char[]{'G', 'H', 'I'});
store.put(5, new char[]{'J', 'K', 'L'});  
store.put(6, new char[]{'M', 'N', 'O'});  
store.put(7, new char[]{'P', 'R', 'Q', 'S'});  
}
  
public static void phoneNum2String(int[] phone){
  char[] curr = new char[phone.length];
  phoneNum2StringRec(phone, 0, curr);
} 
  
private static void phoneNum2StringRec(int[] phone, int index, char[] curr){
  int len = phone.length;
  if(index==len)
    System.out.println(curr);
  else{
    char[] chars = store.get(phone[index]);
    for(char c : chars){
      curr[index] = c;
      phoneNum2StringRec(phone, index+1, curr);
    }
    
  }
}