Скачать или смотреть Sorting an ArrayList by CPM Numbers to Find the Top Values

Learn how to sort an ArrayList by CPM numbers and retrieve the top values efficiently using Java.
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This video is based on the question https://stackoverflow.com/q/66573646/ asked by the user 'Summawata' ( https://stackoverflow.com/u/15371385/ ) and on the answer https://stackoverflow.com/a/66573878/ provided by the user 'WJS' ( https://stackoverflow.com/u/1552534/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Sorting an ArrayList by CPM Numbers to Find the Top Values

If you're working with data analytics in Java, you might sometimes face the issue of sorting and filtering datasets based on specific criteria. In this guide, we'll tackle a common problem: how to sort an ArrayList containing Date/Time and CPM numbers according to the maximum CPM values and keep only the top 5 entries.

Understanding the Problem

Imagine you have a dataset where each entry consists of a timestamp and a CPM (Counts Per Minute) value, like this:

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Your task is to read this data from a file, parse it into an ArrayList of Geiger objects, sort the ArrayList by CPM values in descending order, and keep only the top 5 entries.

Step-by-Step Solution

Let's break down the solution into several clear steps:

Step 1: Define the Geiger Class

First, we need a class to represent each entry in your data. This class should contain attributes for the date and CPM, as well as a method to sort based on CPM.

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Step 2: Read the Input Data

Next, we'll read the data lines from a text file. We're interested in lines that contain the phrase "Every Minute."

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Step 3: Parse the Data into Geiger Objects

We'll split each line based on the commas and create instances of the Geiger class.

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Step 4: Sort the Data and Limit the Results

Now, using a comparator, sort the Geiger objects by CPM values in reverse order, so that the highest values come first. Finally, limit the results to the top 5 entries.

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Step 5: Display the Results

Once you have the top 5 Geiger entries, print them out.

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Full Code Sample

Putting all these steps together, here is the complete code:

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Conclusion

By following these steps, you can successfully read data from a file, process it, sort it by CPM, and find the top entries with ease. This method not only organizes your data but also allows you to analyze trends effectively. Happy coding!