Debugger tutorial

This is a basic tutorial which explains how to use the debugger with a Groovy script.

Overview

We will define a Script interface, and create a debugger session using the SwingDebugScriptWindow.

Define the Script interface

Our interface will be very simple. We will have the following definition for the interface.

   public interface Script {
     public int computeResult(int value) {
     }
   }

Create the debugger session

Define the script interface

First we create a Groovy wrapper with our script interface:

   DebuggingWrapper<Script> wrapper = new GroovyScriptWrapper<Script>() {
   };

Create the SwingDebugScriptWindow

Then we create a SwingDebugScriptWindow and set it as a Debug listener of the wrapper:

   SwingDebugScriptWindow debugWindow = new SwingDebugScriptWindow(20, 20);
   debugWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   wrapper.setDebugListener(debugWindow);

Create the Debug session

Finally we get the script, install it, and create the associated Debug session:

   debugWindow.setVisible(true);

   JFileChooser chooser = new JFileChooser("Open Script");
   chooser.setCurrentDirectory(new File(System.getProperty("user.dir")));
   chooser.setDialogType(JFileChooser.OPEN_DIALOG);
   chooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
   File file = null;
   int ret = chooser.showOpenDialog(null);
   if (ret == JFileChooser.APPROVE_OPTION) {
   file = chooser.getSelectedFile();
   }

   wrapper.initializeDebugSession();
   wrapper.installScript(file);
   DebugSession<Script> session = wrapper.createDebugSession();
   session.setExecutionMode(ScriptWrapper.MODE_NON_BLOCKING);
   session.setSessionHook(new SessionHook<Script>() {
      public void start(Script script) {
        script.computeResult(10);
      }
   });

   session.startSession();

Complete code

The complete code is:

   public class DebugTutorial {
     public void startDebug() throws Exception {
       DebuggingWrapper<Script> wrapper = new GroovyScriptWrapper<Script>() {
       };
       SwingDebugScriptWindow debugWindow = new SwingDebugScriptWindow(20, 20);
       wrapper.setDebugListener(debugWindow);
       debugWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       debugWindow.setVisible(true);

       File file = openScript();
       if (file == null) {
         System.exit(0);
       }
       wrapper.initializeDebugSession();
       wrapper.installScript(file);      
       DebugSession<Script> session = wrapper.createDebugSession();
       session.setExecutionMode(ScriptWrapper.MODE_NON_BLOCKING);
       session.setSessionHook(new SessionHook<Script>() {
         public void start(Script script) {
           script.computeResult(10);
         }
       });
       session.startSession();
     }

     private File openScript() {
       JFileChooser chooser = new JFileChooser("Open Script");
       chooser.setCurrentDirectory(new File(System.getProperty("user.dir")));
       chooser.setDialogType(JFileChooser.OPEN_DIALOG);
       chooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
       File file = null;
       int ret = chooser.showOpenDialog(null);
       if (ret == JFileChooser.APPROVE_OPTION) {
         file = chooser.getSelectedFile();
       }
         return file;
     }

     public static final void main(String[] args) throws Exception {
       DebugTutorial tutorial = new DebugTutorial();
       tutorial.startDebug();
     }
   }

Use the debugger

We will use for this tutorial the following script:

   public int computeResult(int value) {
     int a = 0;
     for (int i = 0; i < 100; i++) {
       a = a + value;
       context.echo("a = " + a);
     }
     return a;
   }

Start the debugger

Run the DebugTutorial class and select the script. You should see the following window:

Add a breakpoint

We will add a breakpoint on our script. First show the line numbers by left-clicking on the left border of ther window and moving it to the right:

Now right-click on line 5 and select "Add breakpoint":

We can now start the debugger, for example by clicking on the button. We will stop on the line with the breakpoint:

If we look on the "Variables" tab, we see:

If we click on the button again, we see: