Big Java Late Objects
Big Java Late Objects
2nd Edition
ISBN: 9781119330455
Author: Horstmann
Publisher: WILEY
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Chapter 13.2, Problem 6SC
Program Plan Intro

Recursive helper method:

  • The recursive helper method is used to identify how far the recursion has already proceeded or how far it still has to proceed.
  • A task may often be solved by handing it over to a recursive helper method.
  • The recursive helper method can be defined by slightly changing the original recursive method.

Example for recursive helper method:

  • Consider the method “public boolean isPalindrome(int start, int end)” used to check a sentence is palindrome or not. Sometimes this method is inefficient for constructing the new sentences.
  • So, a helper method can be introduced to test whether the substrings are palindrome or not. This would be much better than testing the entire sentence is palindrome or not.
  • Then the original recursive palindrome method would call the recursive helper method to check the entire sentence is palindrome or not. It is given below,

//recursive palindrome method

public boolean isPalindrome()

{

//calling recursive helper method

return isPalindrome(0, text.length() - 1);

}

  • In the above, the method call is not recursive. The “isPalindrome(String)” method calls the helper method “isPalindrome(String, int, int)”.

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