Скачать или смотреть How to Use Properties File in Java to Copy Key Values Effectively

Learn how to use properties files in Java to seamlessly copy key values and achieve dynamic property resolution using Apache Commons Configuration.
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This video is based on the question https://stackoverflow.com/q/73813473/ asked by the user 'Rajith Jayathunga' ( https://stackoverflow.com/u/7051734/ ) and on the answer https://stackoverflow.com/a/73830259/ provided by the user 'Rajith Jayathunga' ( https://stackoverflow.com/u/7051734/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Using Properties Files in Java: Copy Key Values and Assign Them to Another Key

When working with configuration in Java applications, properties files offer an efficient way to manage key-value pairs. A common requirement is to copy a value from one key and use it to generate another key dynamically. In this guide, we will explore how you can achieve this scenario effectively using properties files with Java.

The Problem

Let’s consider a situation where you have a settings.properties file that contains the following contents:

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In the Java code, you would like to load this properties file, set a key value (my.name), and retrieve the value of his.name which uses the same reference to ${name}. The expected output should appropriately replace ${name} with the given value, successfully displaying hisNameIsJohn.

Your Current Approach

You might start with the following Java code to read the properties file:

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Unfortunately, this approach won't yield the expected results since the ${name} placeholder won't be resolved correctly in your output. Let’s explore a solution that tackles this issue head-on.

The Solution: Using Apache Commons Configuration

To resolve the placeholder correctly, we can utilize the org.apache.commons.configuration.PropertiesConfiguration class from the Apache Commons Configuration library. This allows for more robust property management, including variable interpolation features that handle placeholders dynamically.

Step-by-Step Instructions

Add Dependency to Your Project: Ensure you include Apache Commons Configuration in your project’s dependencies. If you’re using Maven, add the following to your pom.xml:

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Load Properties Using PropertiesConfiguration: Modify your code as follows:

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Modify your settings.properties: Ensure it maintains the following format:

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Expected Output

Upon executing the modified code, you will receive the following output:

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Conclusion

By adopting Apache Commons Configuration, you can efficiently manage your properties and dynamically resolve key values. This method not only simplifies the process of copying values but also provides a robust way to handle configurations across your Java applications. Whether you're dealing with dynamic properties or need to set multiple key-value pairs, this approach will help you maintain clean code and achieve the desired results.

We hope this explanation has cleared up how to manipulate properties files in Java. Experiment with your configuration setups and unlock the full potential of properties management!