Sorting Even and Odd Numbers: A Java Guide to Custom Order

Learn to sort even numbers in ascending order and odd numbers in descending order in Java arrays. Understand various implementation techniques to achieve your desired output.
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Sorting Even and Odd Numbers: A Java Guide to Custom Order

Sorting numbers in a specific order can often be a tricky task, especially when you have certain conditions to follow for different types of numbers. One common problem involves sorting even numbers in ascending order while arranging odd numbers in descending order.

The Problem Statement

In this post, we will tackle the problem of sorting an array of integers such that:

Even numbers are sorted in ascending order.

Odd numbers are sorted in descending order.

For example, given the input array {9, 3, 5, 6, 7, 8}, the desired output should be {6, 8, 9, 7, 5, 3}.

Unfortunately, a common pitfall occurs where even numbers become sorted in descending order instead of ascending. In this guide, we'll explore different approaches to solve this issue effectively.

Solution Approaches

There are three straightforward methods you can use to achieve the desired output:

1. Temporarily Make Odd Numbers Negative

One method is to temporarily convert odd numbers to negative values, sort them, and then revert them back. Here’s how you can achieve this:

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

In this code snippet, we flip the check for odd numbers from a check for even numbers.

2. Use a Comparator for Sorting

A cleaner and more modern approach would involve using a custom Comparator while sorting the array. However, this requires using an array of Integer objects instead of primitive int, since the sort method accepts a Comparator only for objects.

Here’s how to implement this:

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

This line sorts the array in reverse order, but remember that it will sort the entire array. You'll need to ensure that the even and odd numbers are considered appropriately in separate steps.

3. Reverse the Sorted Array

Another way to handle this is to sort the entire array first and then flip the array at the end. After sorting, you can reverse the array like this:

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

This snippet will reverse the order of the sorted array, but applying it after the appropriate sorting makes this strategy effective.

Additional Best Practices

While implementing these solutions, consider the following best practices:

Maintain Code Readability: Use curly braces {} even for single statements within loops and conditionals. This enhances code readability.

Prefer Standard Array Declarations: When declaring arrays, opt for int[] arr instead of int arr[], as it aligns better with Java conventions.

Conclusion

Sorting even numbers in ascending order while arranging odd numbers in descending can be achieved in various ways in Java. By understanding the above methods, you can choose the best approach that fits your coding style and the specific requirements of your project. Once implemented correctly, your program will successfully display the even and odd numbers arranged as desired.

If you're struggling with array sorting or would like to explore more complex sorting algorithms, feel free to reach out or comment below!