Groovy

What is Groovy

Apache Groovy is a programming language that positions itself as an alternative to Java, from which it inherits many features.
Groovy is both a static and dynamic language, meaning it can be used as a traditional programming language (like Java) or as a scripting language (similar to Python).

As mentioned, Groovy is inspired by Java: it adopts its syntax and compiles its code into bytecode to be executed by the Java Virtual Machine (JVM).
To put it simply, Groovy could be described as a “simplified Java.” However, let’s take a closer look at its features in comparison to Java.

Groovy Vs Java

As already stated, Groovy openly takes inspiration from Java (as noted on the official website’s homepage), but it simplifies some aspects, making the language easier to learn and improving developer efficiency.

Let’s now review the main syntax differences, with more advanced examples to be covered in later sections:

• Default Access: In Groovy, the default access level for methods and attributes is public, whereas in Java, it is private.
• Getters and Setters: Unlike Java, there is no need to explicitly define accessor methods for attributes, as they are automatically generated by the language.
• String Interpolation: Groovy allows variables to be inserted directly into strings, something not possible in Java.
• Typing: Groovy allows for optional typing, with the type of each variable inferred at runtime. In Java, it is mandatory to specify the type of every variable.

// In Groovy
def name = "John Doe"

// In Java
String name = "John Doe"

• Semicolons: It is not necessary to use a semicolon (;) to indicate the end of a statement.
• Program Execution: Unlike Java, Groovy does not require the definition of a main class for the program to run, as every class is automatically wrapped in a class called Script.

// Java
public class Main {
    public static void main(String[] args) {
        System.out.println("Ciao, mondo!");
    }
}

// In Groovy
println "Ciao, mondo!"

Internally, Groovy translates the above script into:

// Traduzione Groovy
class ScriptName extends groovy.lang.Script {
    @Override
    Object run() {
        println "Ciao, mondo!"
    }
}

Performance

Groovy is generally less performant than Java, though it has significantly improved in this area over the years. The main difference stems from the “convenience” Groovy offers, which simplifies the developer’s job but introduces some overhead.

Some factors contributing to Groovy’s lower performance compared to Java include:

• Dynamic Typing: The type of variables is determined at runtime.
• Dynamic Compilation: Although Groovy can be statically compiled (like Java), some features can only be interpreted at runtime, adding overhead.
• String Interpolation: The final content of a string can only be determined at runtime.
• Syntax: Features such as the lack of explicit getters and setters introduce additional overhead.
• Program Startup: Starting the application takes more time because Groovy needs to manage various dynamic language features, such as string interpolation and dynamic typing.

Examples

For a complete example, a simplified program is available at this link, highlighting some of the key differences, both basic and advanced, between the two languages.

Conclusion

In conclusion, Groovy can be considered an excellent tool to improve developer efficiency, provided that code performance is not the primary concern. With Groovy, it is possible to write high-quality code in less time than with Java, at the cost of slightly lower performance.
On the other hand, if performance is critical, Java should be the preferred choice.