Lecture 25 Objectives [Dec 11]prev next

ART MOMENT:
 

A Game of Tric-Trac Artist: Judith Leyster (1609-1660) Date: 1630-1660 With student id, museum tickets cost only $8

By the beginning of today's class you should

HAVE READ:

• Recursion notes [pp. 651-664]

KNOW:

• The concept of recursion
• How to trace a recursive call using the Debugger in Eclipse [use step into]
• What a base case is in a recursive method definition

BE ABLE TO:

• Write a recursive void method that takes one parameter, a positive int value. When called, the method shall output the value to the console backward. That is, if the argument is 1234, then the value "4321" should be output to the console.

DAILY QUESTION:

• What does the following code do?
   

  /**  * Neemt een geheel en output een Ster voor elke vijf of nul  */ public static void neemt (int n) {   if (n > 0) {      neemt (n/10);      if (n %5 == 0) {         System.out.print ('*');      } else {         System.out.print (n % 10);      }   } }

   

Sample Exam question(s)

1. What is wrong with the following recursive implementation of a search in a LinkedList. This method is found in the NumberNode class:
   
    

   /**  * Recursive implementation  */ public boolean find (int i) {   // base case(s)   if (value == i) {     return true;   }   // recurse onwards!   return next.find(i); }

    

2. Write a recursive solution that prints to the screen all vowels found in a String:
   
    

   /**  * Recursive implementation to print to the screen just the  * vowels of the String.  */ public static void printVowels (String s) {   // base case(s)   // recurse onwards! }