Skip to main content

Beanshell Programming

Basic Syntax​

BeanShell is fundamentally a Java interpreter, making it immediately accessible to those familiar with the Java language. This section outlines the subset of Java that BeanShell supports, along with the enhancements and relaxed syntax it introduces to provide a more flexible, scripting-friendly experience.

Methods​

BeanShell allows defining methods using standard Java syntax, with the added flexibility of optional typing for parameters and return values. Methods can be strictly typed or dynamically typed, enabling them to handle a variety of input types at runtime. When types are omitted, BeanShell determines them dynamically, supporting operations like numeric addition or string concatenation based on context. Return types are also flexible—methods may return a value, return nothing, or implicitly return the result of the final expression if no return statement is provided.

Objects​

BeanShell supports object-oriented scripting by allowing the creation of scripted objects using method closures, similar to constructs found in languages like JavaScript and Perl. While it does not support defining full Java classes, BeanShell enables object-like behavior through a natural extension of its method syntax. This approach allows for encapsulation and reuse, promoting more structured, maintainable scripts. Scripted objects can reference themselves using this, offering a familiar model for those used to Java's object-oriented design.

Modifiers​

In BeanShell, this, super, and global are references to script contexts, acting like objects. They represent the current, parent, and global scopes, allowing methods and scripted objects to share and inherit variables and behavior dynamically.

Interfaces​

A key feature of BeanShell is its support for scripting Java interfaces. This enables creating scripts that act as event handlers, listeners, or components within Java APIs. Scripted interfaces seamlessly integrate with applications, behaving like regular Java objects and simplifying interaction with scripted components.

Special Variables and Values​

Alongside scope modifiers like this, super, and global, BeanShell provides several predefined system variables, special "magic" values, and built-in methods that facilitate scripting and enhance functionality.