Executing Scripts - Scripting in Java: Integrating with Groovy and JavaScript - page 16

Chapter 2

Executing Scripts

In this chapter, you will learn:

eval() method of ScriptEngine to execute scripts

• How to use the

• How to pass parameters from Java code to Nashorn engine

• How to pass parameters from Nashorn engine to Java

Using the eval( ) Method
A ScriptEngine can execute a script in a String and a Reader . Using a Reader , you can
execute a script stored on the network or in a file. One of the following versions of the
eval() method of the ScriptEngine interface is used to execute a script:

Object eval(String script) •

Object eval(Reader reader) •

Object eval(String script, Bindings bindings) •

Object eval(Reader reader, Bindings bindings)

•

Object eval(String script, ScriptContext context) •

Object eval(Reader reader, ScriptContext context)
The first argument of the eval() method is the source of the script. The second
argument lets you pass information from the host application to the script engine that can
be used during the execution of the script.
In Chapter 1, you saw how to use a String object to execute a script using the first
version of the eval() method. In this chapter, you will store your script in a file and
use a Reader object as the source of the script, which will use the second version of the
eval() method. The next section discusses the other four versions of the eval() method.
Typically, a script file is given a .js extension.

•