Important Notice:

Practice-It will be discontinued as of November 1st, 2024. After this date, the website will remain online for a transitional period, but login will be restricted to University of Washington NetID authentication. This marks the next phase towards the platform's full retirement. Thank you for your use and support of the application over the years.

If you are looking for an alternative, a similar tool, CodeStepByStep, was developed independently by the original author of Practice-It, and is available at codestepbystep.com**

logo Practice-It logo

Main Page → Problems → Solve a Problem

indexOf

Language/Type: Java recursion recursive programming
Author: Robert Baxter and Whitaker Brand

Write a recursive method indexOf that accepts two Strings as parameters and that returns the starting index of the first occurrence of the second String inside the first String (or -1 if not found). The table below lists several calls to your method and their expected return values. Notice that case matters, as in the last example that returns -1.

Call Value Returned
indexOf("Barack Obama", "Bar") 0
indexOf("Barack Obama", "ck") 4
indexOf("Barack Obama", "a") 1
indexOf("Barack Obama", "McCain") -1
indexOf("Barack Obama", "BAR") -1

Strings have an indexOf method, but you are not allowed to call it. You are limited to these methods:

Method Description
equals(String other) returns true if the two Strings contain the same characters
length() returns the int number of characters in the String
substring(int fromIndex, int toIndex)
substring(int fromIndex)		 returns a new String containing the characters from this String from fromIndex (inclusive) to toIndex (exclusive), or to the end of the String if toIndex is omitted

You are not allowed to construct any structured objects other than Strings (no array, List, Scanner, etc.) and you may not use any loops to solve this problem; you must use recursion.

Type your solution here:


This is a method problem. Write a Java method as described. Do not write a complete program or class; just the method(s) above.

You must log in before you can solve this problem.


Log In

If you do not understand how to solve a problem or why your solution doesn't work, please contact your TA or instructor.
If something seems wrong with the site (errors, slow performance, incorrect problems/tests, etc.), please

Is there a problem? Contact a site administrator.