Java8 Nashorn

Nashorn is a new JavaScript engine in Java 8 that can be used to execute JavaScript code from Java programs. Nashorn is faster and has better memory efficiency than the previous JavaScript engine, Rhino.

Benefits of Nashorn

1. Performance: Nashorn is a significant improvement over the old Rhino engine. Nashorn is typically two to ten times faster than Rhino, which makes it a more suitable engine for many applications.

2. Memory Efficiency: Nashorn is designed to use less memory than Rhino. This means that you can execute JavaScript code within a Java program without consuming too much memory.

3. Integration with Java: Nashorn has built-in support for Java classes and objects. This makes it easy to add JavaScript code to an existing Java application.

4. Lambda Support: Nashorn provides support for lambdas, which are a new language feature in Java 8. This makes it easier to write JavaScript code that is more concise and expressive.

5. Debugging Support: Nashorn provides a debugging API that allows developers to debug JavaScript code using the same tools they use for Java. This makes it easier to diagnose and fix issues in JavaScript code.

Using Nashorn in Java Programs

Here's a simple example of using Nashorn in a Java program:

import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

public class Main {
    public static void main(String[] args) {
        ScriptEngineManager manager = new ScriptEngineManager();
        ScriptEngine engine = manager.getEngineByName("nashorn");

        try {
            engine.eval("print('Hello, World!')");
        } catch (ScriptException e) {
            System.err.println(e.getMessage());
        }
    }
}

In this example, we use the ScriptEngineManager class to get an instance of the Nashorn engine. We then execute a simple JavaScript program that prints "Hello, World!". Finally, we handle any exceptions that occur during execution.

Conclusion

Nashorn is a powerful JavaScript engine that provides a fast and efficient way to execute JavaScript code from Java programs. With its built-in support for Java classes and objects, it's easy to integrate JavaScript code into a Java application. And with its support for lambdas and debugging, it's an excellent choice for developing complex applications that require both Java and JavaScript functionality.