How to Fix java.util.NoSuchElementException When Retrieving Next String in Java

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Understanding the Problem

The goal of the code is to implement a method that retrieves the string that follows a line starting with a specified string in an ArrayList. The key functionalities include:

Getting the string that follows the line that starts with a given string.

Returning the string found on the next line, or null if the given string does not exist.

Common Scenarios

Scenario 1: An ArrayList named lines contains "hello" and "world". If you call getNextStringStartsWith("hello"), you expect "world" as the output.

Scenario 2: If the list includes "Course" and "CIT590" and you look for getNextStringStartsWith("Course"), the output should be "CIT590".

Scenario 3: For the input getNextStringStartsWith("goodbye"), if the list contains "hello" and "world", the result should be null since the string does not exist.

However, let's say you implemented this method but encountered a NoSuchElementException. This usually happens when you try to access an element from an iterator that does not exist (like calling next() without checking hasNext() properly).

The Solution

To effectively resolve this issue, you need to ensure that your logic correctly checks for the presence of elements before trying to access them. Here’s an illustrated solution:

Basic Structure of the Method

Begin by defining your method with the following structure:

[[See Video to Reveal this Text or Code Snippet]]

Improved Logic

Step 1: Iterating Through the List

Within the loop, you need to check if the current string matches the input string str.

Step 2: Retrieve the Next Element Safely

Before trying to access the next element, always ensure it exists:

[[See Video to Reveal this Text or Code Snippet]]

Complete Method Implementation

Here’s the complete corrected method:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Final Thoughts

Always consider edge cases and ensure your conditions provide robust safeguards against exceptions. With practice, handling exceptions in Java can become a breeze!

Hope this helps you resolve the issue in your Java code. Happy coding!