Understanding the java Cannot resolve method 'contains(int)' Error: A Simple Fix

Learn how to resolve the `java Cannot resolve method 'contains(int)'` error by converting an `int` array to a `List Integer `. Get insights and clear code examples to avoid common pitfalls in Java arrays and lists.
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Understanding the java Cannot resolve method 'contains(int)' Error: A Simple Fix

When programming in Java, encountering errors can be frustrating, especially those that seem difficult to decode. One common issue developers face is the Cannot resolve method 'contains(int)' error. If you've come across this message, you're not alone. Let's break down the problem and find a straightforward solution.

The Problem

In the code snippet provided, the following code snippet was responsible for triggering the error:

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

The intention behind the if statement was to check whether a specific year (1919) is included in the array of years. However, the output was incorrect, resulting in "Not contains". This was perplexing as 1919 is indeed a part of the YEARS array.

Understanding the Cause

The contains Method: The contains(int) method of a List checks for the presence of an Integer, but since you provided an array, it doesn't find the match, leading to an unexpected result.

The Solution: Creating a List of Integers

To fix the issue, you should convert the integer array to a List<Integer>. This can be achieved by using Java Streams. Here's how to implement that change:

Step-by-Step Solution

Boxing: Utilize the boxed() function to convert each of the primitive integers to their corresponding wrapper objects (Integer).

Updated Code Example

Here's how your code should look after implementing these changes:

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

Conclusion

By properly converting the int[] to a List<Integer>, you can now effectively use the contains method to check for the presence of integers. This solution not only resolves the error but also reinforces the importance of understanding the differences between primitive types and their wrapper classes in Java.

If you continue to face similar challenges, remember that debugging is a part of the learning process. Happy coding!