phoneNum2StringIter.java

public static void phoneNum2StringIter(int[] phone){
  int len = phone.length;
  char[] curr = new char[phone.length];
  for(int i=0;i<phone.length; i++)
    curr[i] = store.get(phone[i])[0];
  System.out.println(curr);
  while(findNext(phone, curr)){
    System.out.println(curr);
  }
  
}
  
private static boolean findNext(int[] phone, char[] curr){
  //we loop through from right
  for(int i=phone.length-1;i>=0;i--){
    char[] chars = store.get(phone[i]);
    int found = -1;
    for(int index = 0; index<chars.length; index++)
      if(chars[index] == curr[i])
        found = index;
    
    if(found!=-1 && found+1<chars.length){
      //we find the index of curr[i] and set it to next char
      curr[i] = chars[found+1];
      //also set all of the chars to its right to mimimum values 
      for(int j=i+1;j<phone.length;j++){
        curr[j] = store.get(phone[j])[0];
      }
      return true;
    }
    
  }
  return false;
}