Скачать или смотреть Custom Method Reference in Java: Understanding Parameterized Method Calls with Reflection

Learn how to implement custom method references in Java using interfaces and reflection. This guide offers a step-by-step approach with code examples to help you pass methods for execution.
---
This video is based on the question https://stackoverflow.com/q/63503116/ asked by the user 'Keker' ( https://stackoverflow.com/u/11233636/ ) and on the answer https://stackoverflow.com/a/63506540/ provided by the user 'Ironluca' ( https://stackoverflow.com/u/3883475/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Custom method reference

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Custom Method Reference in Java: Understanding Parameterized Method Calls with Reflection

In the world of Java programming, method references provide a succinct way to refer to methods without executing them. However, when you want to pass a method with parameters to an interface, things can get a bit tricky. Many developers wonder: Is it possible to create a method reference with parameters? In this guide, we will tackle this question and explore a practical solution using Java's reflection capabilities.

The Problem Statement

The crux of the problem is as follows: you want to create an interface that can execute a method for both the current object and a parameter object. Specifically, you are interested in creating a customEquals method in a class that utilizes a predicate to compare two objects via their getter methods.

Here's a snippet illustrating the concept:

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

In this example, ClassType is the class where the customEquals method is declared, and MethodReference is a reference to a specific getter method.

The Solution: Using Reflection

It is indeed possible to achieve this using reflection in Java. Let's break down the solution into a few components:

1. Define the Interface

First, you'll need to create an interface that specifies a method to execute another method. Here's how you can define a simple interface:

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

This interface contains a single method exec that takes a Method object and two parameters for execution.

2. Implement the Interface

Next, you will implement this interface in a class. Here’s an example implementation:

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

In this class, the simpleMethod adds two integers. The exec method uses reflection to invoke the specified method on the current object with provided parameters.

3. Testing the Implementation

To see this in action, you'll need a main method that tests out your implementation:

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

This SimpleTester class retrieves a method reference for simpleMethod and invokes it by passing the necessary parameters (1 and 2), showing how reflection can help you achieve the desired functionality.

Conclusion

Understanding how to use method references with parameters in Java can greatly enhance your coding efficiency and flexibility. By leveraging Java's reflection capabilities, you can create powerful interfaces and dynamically invoke methods as necessary.

Remember, the example provided uses JDK8 and illustrates just one of the ways to achieve this functionality. With this knowledge, you can explore further applications and refine your Java programming skills.

Feel free to adapt this approach to your specific implementations and requirements. Happy coding!