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BJP4 Exercise 12.13: indexOf

Language/Type: Java recursion recursive programming
Author: Robert Baxter (on 2016/09/08)

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.

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