Question

Java class quiz need help~

This is the Backwards.java code.

public class Backwards {

   /**
    * Program starts with this method.
    * 
    * @param args A String to be printed backwards
    */
   public static void main(String[] args) {
      if (args.length == 0) {
         System.out.println("ERROR: Enter a String on commandline.");
      }
      else {
         String word = args[0];
         String backwards = iterativeBack(word); // A (return address)
         System.out.println("Iterative solution: " + backwards);
         backwards = recursiveBack(word); // B (return address)
         System.out.println("\n\nRecursive solution: " + backwards);
         backwards = recursiveBack2(word); // C (return address)
         System.out.println("\n\nRecursive solution2: " + backwards);
         System.out.println();
      }
   }

   /**
    * Writes a character string backward using iteration.
    * 
    * @param s a character string
    * @return a backwards string
    */
   public static String iterativeBack(String s) {
      int len = s.length();
      String backWord = new String();
      for (int i = len - 1; i >= 0; i--) {
         backWord = backWord + s.substring(i, i + 1);
      }
      return backWord;
   }

   /**
    * Writes a character string backward using recursion.
    * 
    * @param s a character string
    * @return a backwards string
    */
   public static String recursiveBack(String s) {
      int len = s.length();
      // base case: output string if only has one character
      if (len == 1) {
         return s;
      }
       // recursive case: display last character,
       // then call method again with shorter string
       // that has the last character cut off
      else {
         return s.substring(len - 1, len)
              + recursiveBack(s.substring(0, len - 1));
         // D (return address)
      } // end of else
   } // end of recursiveBack()

   /**
    * Writes a character string backward using recursion.
    * 
    * @param s a character string
    * @return a backwards string
    */
   public static String recursiveBack2(String s) {
      int len = s.length();
      System.out.println("String: " + s);
      System.out.println("Length: " + len);
      // base case: output string if only has one character
      if (len == 1) {
         System.out.println("return: " + s);
         return s;
      }
       // recursive case: call method again with shorter string
       // that has the first character cut off,
       // then display first character
      else {
         System.out.print("return: recursiveBack2(s.substring(1,len))");
         System.out.println(" + " + s.substring(0, 1));      
         return recursiveBack2(s.substring(1, len)) + s.substring(0, 1);
         // E (return address)
         
      } // end of else
   } // end of recursiveBack2()

} // end of class

The question is :Using the Backwards.java program

• Do a box trace of a call to second recursive method recursiveBack2 (starts on line 73)
• Use the string "dog" as the input parameter.
• This should be very similar to what was done in the slides in the Lecture on Recursion pt 1, starting on slide 34.
• Each activation record (ARI) (box) should have the return address (as shown in the code comments), the parameter(s), local variable(s), and the return value at each step.
• Draw a new set of ARIs for each step

can do a hand drawing or on the computer, thank you!!

Answer 1