The Groovy Swing Console allows a user to enter and run Groovy scripts. This page documents the features of this user interface.
The Groovy Console:
- The Console has an input area and an output area.
- You type a Groovy script in the input area.
- When you select "Run" from the "Actions" menu, the console compiles the script and runs it.
- Anything that would normally be printed on System.out is printed in the output area.
- If the script returns a non-null result, that result is printed.
Handy tips for running scripts:
- Ctrl+Enter and Ctrl+R are both shortcut keys for "Run Script".
- If you highight just part of the text in the input area, then Groovy runs just that text.
- The result of a script is the the value of the last expression executed.
- You can turn the System.out capture on and off by selecting "Capture System.out" from the "Actions" menu
You can open any text file, edit it, run it (as a Groovy Script) and then save it again when you are finished.
- Select File -> Open (shortcut key ctrl+O) to open a file
- Select File -> Save (shortcut key ctrl+S) to save a file
- Select File -> New File (shortcut key ctrl+Q) to start again with a blank
History and results
- You can pop-up a gui inspector on the last (non-null) result by selecting "Inspect Last" from the "Actions" menu. The inspector is a convenient way to view lists and maps.
- The console remembers the last ten script runs. You can scroll back and forth through the history by selecting "Next" and "Previous" from the "Edit" menu. Ctrl-N and ctrl-P are convenient shortcut keys.
- The last (non-null) result is bound to a variable named '_' (an underscore).
- The last result (null and non-null) for every run in the history is bound into a list variable named '
__' (two underscores). The result of the last run is
_[-1], the result of the second to last run is
[-2]and so forth.
- You can attempt to interrupt a long running task by clicking the "interrupt" button on the small dialog box that pops up when a script is executing.
- You can change the font size by selecting "Smaller Font" or "Larger Font" from the "Actions menu"
- The console can be run as an Applet thanks to groovy.ui.ConsoleApplet
- Code is auto indented when you hit return
- You can drag'n drop a Groovy script over the text area to open a file
- You can modify the classpath with which the script in the console is being run by adding a new JAR or a directory to the classpath from the Script menu
- Error hyperlinking from the output area when a compilation error is expected or when an exception is thrown
Embedding the Console
To embed a Swing console in your application, simply create the Console object,
load some variables, and then launch it. The console can be embedded in either Java or Groovy code.
The Java code for this is:
Once the console is launched, you can use the variable values in Groovy code.
An example of how to embed either the GroovyConsole or GroovyShell in a Spring Web application can be found at Embedding a Groovy Console in a Java Server Application
Visualizing script output results
You can customize the way script output results are visualized. Let's see how we can customize this. For example, viewing a map result would show something like this:
What you see here is the usual textual representation of a Map. But, what if we enabled custom visualization of certain results? The Swing console allows you to do just that. First of all, you have to ensure that the visualization option is ticked: View -> Visualize Script Results — for the record, all settings of the Groovy Console are stored and remembered thanks to the Preference API. There are a few result visualizations built-in: if the script returns a java.awt.Image, a javax.swing.Icon, or a java.awt.Component with no parent, the object is displayed instead of its toString() representation. Otherwise, everything else is still just represented as text. Now, create the following Groovy script in ~/.groovy/OutputTransforms.groovy:
The Groovy Swing console will execute that script on startup, injecting a transforms list in the binding of the script, so that you can add your own script results representations. In our case, we transform the Map into a nice-looking Swing JTable. And we're now able to visualize maps in a friendly and attractive fashion, as the screenshot below shows:
In Groovy 1.7 (not yet released), it'll be possible to visualize the AST (Abstract Syntax Tree) representing the currently edited script, as shown by the screenshot below. This is particularly handy when you want to develop AST transformations.