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Learn how to create your own `contains` method in Java using a LinkedList. We'll break down the solution step-by-step, making it easy to understand!
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This video is based on the question https://stackoverflow.com/q/64585030/ asked by the user 'mirkovski' ( https://stackoverflow.com/u/14514769/ ) and on the answer https://stackoverflow.com/a/64585080/ provided by the user 'Blake' ( https://stackoverflow.com/u/7571925/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Write a contains Method in Java for LinkedList

Have you ever found yourself needing to check if a particular element exists in a Java LinkedList? If so, you might be tempted to use the built-in contains method. However, it's also a great learning experience to build your own method to do this! Today, we're going to focus on how to write a custom contains method using a LinkedList. Let’s take a look at a common problem and how to solve it effectively.

The Problem: Creating a Custom contains Method

A user faced a common challenge: implementing a method that would check if a specified integer is present in a LinkedList. The initial attempt resulted in the method always returning false. Here's a quick look at some code that illustrates the issue:

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

What's Wrong with the Code?

The issue stems from the fact that the current implementation is trying to compare a LinkedList object to an integer using .equals(), which will always yield false because they are of different types.

The Solution: Implementing the contains Method

To resolve the issue, we need to iterate through the elements of the LinkedList and check if any of them match the integer we're searching for. Below is the corrected implementation of the search method.

Updated search Method

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

Explanation of the Code

For-Each Loop: We utilize a for-each loop to iterate through each element in the list. This is efficient and keeps the code concise.

Comparison: Inside the loop, we check if the current item equals the integer i. If we find a match, we immediately return true.

Return False: If the loop completes without finding any matches, we return false to indicate that the integer does not exist in the LinkedList.

Putting It All Together

Here’s the complete code snippet with the new search method:

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

Conclusion

Creating your own method to determine if an element exists in a LinkedList is a valuable exercise in understanding Java’s collection framework. By using a simple for-each loop, you can effectively search through the list and return the appropriate boolean value based on the presence of the specified integer. With this custom contains method, your Java programming skills will surely grow!