What Modernization of Legacy Java Should Look Like?

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Monolithic applications are the norm for old Java apps; they include everything required to run the project in a single package. Recompiling, testing, and reloading the entire app after each change made, however, might slow developers down. Taking advantage of cloud computing, adding new elements to the existing app, and upgrading the Java collection framework can help launch new and improved products quickly.

If you’re unsure how to approach the process of modernization, read this article. We have some tips for you.

What Is Legacy Modernization?

Historical Java software programs often rely on a monolithic stack class architecture, making it difficult to maintain and update the application as a whole. This is because changes to a single legacy class can require recompiling and redeploying the entire stack, leading to slow development cycles and potential bugs.

Traditional Java applications can, however, regain their nimbleness and improve the user experience through application modernization, which entails moving them to a more up-to-date platform, splitting up their monolithic structures into smaller, more manageable parts (such as microservices), using modern back-end development services and deployment practices, and integrating their architecture with that of newer, more advanced systems.

The Benefits of Modernizing Legacy Java

If your company is still using an old system, updating it to a more modern one will help you offer your customers better products and services. If you are willing to invest in an upgrade, you can modernize user interfaces, create new features, automate repetitive operations, and introduce new services to the market. But there are more benefits to the modernization process. See how you can benefit from upgrading from an older version of Java.

Improve efficiency by containerizing outdated Java apps that run on virtual machines and are typically resource hogs. Modernizing your application is an excellent place to start if you want to make the most of your computer resources and adapt swiftly to shifting demands.

Launch new products and services swiftly. Adhering to current industry standards allows you to deliver updates faster and set up pipelines and containers that support frequent deployments, accelerating time to market.

Create apps that can withstand the test of time and are prepared for the future using microservices, which help break down business processes into smaller, more manageable elements. Using a microservices architecture to build your program means you can make changes to specific parts of it without affecting the whole.

Increase safety. As time passes and technology evolves, security flaws can creep into even the most well-designed legacy app. The implementation of application modernization measures can prevent these problems.

Why Modernize Java Applications?

Agility, cost-effectiveness, and improved experience – need we say more? Probably not, but let’s dig deeper into the reasons for switching to an upgraded solution. As mentioned before, with cloud computing, microservices building, and methods such as containerization, you can use Java development services and build more, better, and faster.

Default monolithic applications have flaws that can be addressed quickly with modern technologies, which saves time and money. Moreover, when official support for the platforms or servers you’ve utilized has ceased, or no developer can update the code, the cost of running legacy programs can skyrocket.

Modernization of Legacy Java

Modernization Strategies for Legacy Java

You can create new versions of your existing apps with modernized Java in several ways. Choosing the right method will depend on your technical abilities and functionality needs. Learn which processes best support application upgrades.

Rehost Path

To adopt a rehosting method, you would move your existing infrastructure to the cloud, which would entail migrating your existing apps. The hosting environment is usually on-site, so the process is called a “lift and shift.”

Rehosting is a common strategy for businesses moving to the cloud. It’s also a go-to choice for companies trying to speed up their migration and get where they need to be regarding their operations. This is because rehosting does not always demand high levels of technical skill. While this approach is generally more straightforward and requires less expertise, it may not fully take advantage of cloud computing or provide the same value as, for example, replatforming.


The main difference between rehosting and replatforming is the addition of cloud optimization as a critical element in the latter process. When replatforming an application, specific optimizations are added to improve its performance and value in the cloud environment, such as adjusting parameters to suit the new platform better.

This additional step is the primary reason why replatforming is a more complex method and requires a greater level of expertise than rehosting. However, the benefits of replatforming can be significant, as it allows organizations to fully leverage the capabilities of the cloud environment and optimize an existing app.


Legacy classes were developed years ago and may no longer meet current coding standards. Refactoring involves improving the structure and design of these classes without changing their behavior, making them easier to maintain and enhancing their performance.

Using Java Web Start for Refactoring

One way to upgrade old Java apps is by introducing Java Web Start. It’s a tool that enables applications to be launched from a browser without requiring manual installation or updates. Modernizing apps this way involves refactoring the code to make use of Java Web Start features, such as automatic updates, caching, and sandboxing.


Rearchitecting a legacy application’s current architecture while maintaining its essential business logic and incorporating fresh elements involves applying advanced computing techniques. This strategy is generally used when the program adds new functionality and handles new requirements.

The rearchitecting procedure frequently entails adopting a new stack, enabling developers to take advantage of cutting-edge technology and enhance the overall performance and scalability of the app. Rearchitecting Java apps can be time-consuming and expensive, but it has many benefits, including improved performance, scalability, and usefulness.

Automating Legacy Java Modernization

Automating Java modernization involves using software tools to update legacy applications. By automating the process, businesses can save time and reduce the risk of errors or bugs that may arise during manual modernization. For example, automated tools can identify and update legacy classes without requiring developers to search for each one manually.

Furthermore, automation tools can also help identify and update specific app elements that may need modernization. Streamlining the process allows you to modernize old Java apps more efficiently and deliver new features to users faster.

The automated conversion method keeps the functionality and user interfaces of the current program while transferring legacy data and code to modern platforms. This approach may be quicker and more precise than standard reengineering or off-the-shelf software.

Why Migration Is a Good Time to Rebuild the Application?

During application migration, it may be necessary to rebuild the app to ensure it is compatible with the new environment. The rebuilding process involves reviewing its code, dependencies, and configurations and making essential changes to remain functional.

Migration is an excellent opportunity to rewrite an app from the ground up and fix problems like a bloated stack, obsolete technology, or poorly designed data structures. For example, if an application uses a collections framework like the vector class, which has performance issues due to its synchronization mechanisms, migration could be an opportunity to switch to a more modern collection class that performs better.

Similarly, if an application uses the properties class to manage configuration files, which can be challenging to maintain and scale, the migration process could be an opportunity to move to a more robust and flexible configuration management solution.


Modernizing Java applications is crucial for businesses to keep pace with the rapidly evolving technology landscape. As this article outlines, migrating to a modern platform, adopting microservice architecture, and upgrading legacy classes and codebases can help address common issues like technical debt and performance bottlenecks. Using these methods, businesses may fix Java application problems like technical debt, slow performance, and vulnerabilities and develop easier-to-update and scale products.

If you need help with the process, contact our Software Development Company. We’re ready to help!

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