Refactoring Legacy Codes: Tools and Techniques
Published: 2023-02-06 12:45:44

## What is Code refactoring? 

Code refactoring is altering and restructuring an application's code, while its functions and external behavior remain the same. The process helps to replace the older code base with modern ones. Refactoring makes codes reusable, easier to understand, and more easily modified. The needs and the anticipations of everyday consumers have made application refactoring a must, which means that developers must spend most of their time reading and restructuring codes.

![Refactoring Legacy Codes](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/ukndr2rs8rjgv460yn3u.png)

A legacy code is outdated application source code that is expected to be practiced and adapted. It is a code that is subject to renovation and re-implementation. Refactoring legacy code helps to renew its value with recent modern approaches. The process is crucial especially for applications that are already on the market and making money with an established customer base. Legacy codes can have issues such as poor documentation, complexity, errors, plagiarism, etc.

Without the right skill set, refactoring a legacy code could be risky because of the possibility of app’s dysfunctionality. However fixing legacy code isn’t impossible, AppRefactoring tools help to analyze, compare the new codes with existing projects and refactor your legacy codes.

## Advantages of Code Refactoring

There are several purposes of code refactoring, developers consider restructuring codes for these reasons:

- **Improved Readability:** The experience of reading codes can improve by enhancing our readability which makes it easier to understand what the app does.
- **Code Maintenance:** You could realize that your codes are complicated after completing your projects. If you do not pay attention to existing codes, you may write duplicate codes, or too many parameters. Cleaning up your codes reduces complexity and makes your codes maintainable. Paying attention to refactoring early in your project helps prevent errors in your codes later.
- **Better Performance:** It effectively boosts application code performance and overall execution speed of all the app functions.
- **Bug Prevention & Repairs:** You alter the codes to resolve bugs as you advance and understand more about your project.
- **New Functionality:** Adding new functions to applications becomes easier after refactoring is done.
- **New Technology Implementation:** Restructuring application codes supports the implementation of newer technologies unavailable during the app's initial development process.
- **Code Uniqueness:** Many developers use legacy code as a base code for developing new applications. In this case, it may be necessary to uniquely code the application being developed.

The main problem that comes with refactoring isn't the codes, but the need for proper tools. If you want to build a high-quality solution for your application and check the uniqueness of your codes, AppRefactoring has the most appropriate tools.


![Legacy Code Refactoring](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/kd0y0m5krmx70s5t9ih8.png)

## When is Code Refactoring Necessary?

## Development Stage:
 If you put out an inferior product and do not pay attention to refactoring in the development process, consumers might not use your product again. Code rot could decrease the performance of your products or introduce bugs, create a great first impression by analyzing your code while developing.

## Before Updates:
 New updates or features should not be added to your codes during refactoring. Cleaning up your current codes before adding new functions improves the quality of the product and makes it easy for developers to build on the codes in the future.

## Post Launch:
 Returning to refactor your codes even after putting your product out to the market gives developers enough time to work on existing codes.

## Example of Legacy code Refactoring

Here is an example of refactoring legacy code in Java:

```
public class LegacyCode {
    public void processData(List<String> data) {
        List<String> cleanedData = new ArrayList<>();
        for (String dat : data) {
            if (dat.startsWith("#")) {
                continue;
            } else if (dat.endsWith("!")) {
                cleanedData.add(dat.substring(0, dat.length() - 1));
            } else if (dat.endsWith(".")) {
                cleanedData.add(dat.substring(0, dat.length() - 1));
            } else {
                cleanedData.add(dat);
            }
        }
    }
}
```

This code takes a List of strings called data and processes it to remove certain characters from the end of the strings. However, the code is hard to read and understand. Here is an example of how it could be refactored:

```
public class LegacyCode {
    public List<String> processData(List<String> data) {
        return data.stream()
                .filter(dat -> !dat.startsWith("#"))
                .map(this::removePunctuation)
                .collect(Collectors.toList());
    }
    
    private String removePunctuation(String dat) {
        return dat.replaceAll("[!.]", "");
    }
}
```

This refactored version of the code is more readable and it makes use of functional programming concepts (Stream, filter, map, and Collectors) which is more elegant and efficient. Additionally, the removePunctuation() method is reusable and can be used in other parts of the codebase.
It's important to note that this is a simple example, and the refactoring process for larger and more complex codebases will likely involve more extensive changes.

## Refactoring Tools

Carrying out your legacy code refactoring exercise manually, takes a lot of time and resources. It is therefore best to make use of an automated tool like [AppRefactoring](https://apprefactoring.com/). AppRefactoring is a tool that helps with identifying intersections and duplicates in project codes and thus provides recommendations for refactoring. It is available for several programming languages such as Java, Swift, Javascript, Typescript, Kotlin, C#, Objective-C, PHP and GO. 

AppRefactoring offers a modern interface that allows you to quickly and efficiently analyze and uniquely identify the application code, thereby reducing the risk of getting banned by the App Store and Google Play by up to 90%. The tool has support for mobile platforms, IOS, Android, and Unity.

## Conclusion

Refactoring legacy code could be difficult because it could be time consuming, but it is essential for stable applications. Ignoring refactoring results in “code rot” such as duplicate codes, large classes & too many responsibilities per class, and unhealthy dependencies between classes. It is crucial to consider continuous refactoring to keep off all these problems. 

Refactoring is a continuous process to extend the life of your application, which is especially important for applications based on legacy code. It is important to regularly clean your code for a better product and improved performance. Using the proper tools gives you the best result when refactoring your legacy code. AppRefactoring analyzes your code, comparing it to other programs in your database before returning recommendations on refactoring and obfuscation.