Transform JSON Structure in Java: Grouping Data with Common Values

Learn how to restructure JSON data in Java by grouping items with a common value and organizing others into lists.
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Transforming JSON Structure in Java: Grouping Data with Common Values

In the world of programming, especially when working with data transfer objects (DTOs) and JSON, you may encounter scenarios where you need to manipulate the structure of JSON data. One such common task is to transform a JSON object that contains duplicated values into a more organized format. In this guide, we’ll address the problem of grouping JSON items by a common value while structuring the rest of the values into a list. Let's take a closer look at the problem and provide a detailed solution.

The Problem: Restructuring JSON Data

Imagine you have JSON data where multiple objects contain a common field (resourceName), but other fields are unique. The goal is to consolidate these objects into a single object that captures the common value and lists the varying attributes.

Example of Input JSON:

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Desired Output JSON:

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Now that we understand the problem, let's break down the solution step by step.

The Solution: Step-by-Step Implementation

1. Define the DTO Classes

First, you will need to define Java DTO classes representing both your input and output JSON structures. Using Lombok annotations can simplify this.

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2. Create the Output DTO Class

Next, define the class for the expected output that captures the common resource name and groups the months into a list.

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3. Transform Input JSON to Output JSON

Once the DTOs are set, utilize the ObjectMapper to parse the input JSON and then use Java Streams to transform it. Here’s how you'd do it:

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4. Serialize the Result to JSON

Finally, you can serialize the remap object back to JSON to observe the structured output.

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Resulting Output

You would get the desired output, neatly formatted as:

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Conclusion

Transforming JSON structures in Java using DTOs and powerful Stream operations can simplify your data handling processes. In this post, we discussed how to reshape JSON data effectively to cater to specific programming needs. By following the steps outlined, you can ensure your data is both elegantly structured and easily maintainable. Happy coding!