-- Creating and configuring a Checkstyle configuration --

We learned how to set up a project to be checked with the Checkstyle Plug-in in the previous chapter .

Now we want to create our own Checkstyle configuration.

  1. Open the Eclipse Preferences Window

    Open Eclipse preferences

  2. Navigate to the Checkstyle section within the Eclipse preferences

    Checkstyle preferences
    The Checkstyle preferences should look like this. In the upper area are some general settings which will be explained later in detail.
    The center/bottom area shows the Checkstyle configurations known to the plug-in. Only Checkstyle Configurations that are listed therein can be used with the plug-in.
    Note the Sun Checks configuration which we used in the previous chapter as check configuration for our project.
    Sun Checks is a built-in standard configuration that comes delivered with Checkstyle and therefore also with the plug-in. Built-In configurations cannot be modified nor be deleted.

  3. Click the New... button to create a new checkstyle configuration

    Check Configuration properties
    The Check Configuration Properties dialog comes up. Its quite empty so we must provide some data to create our Checkstyle configuration.
    At first we must decide which type of configuration we would like to create. There are several configuration types - each suitable for specific use cases.
    Don't mind all these types for now - for starters we will be creating a Internal Configuration.
    Note that the location text field will be grayed out as you select this configuration type. This is because internal configurations are stored deep within the bowels of the eclipse workspace.
    The plug-in will create a unique filename for our new configuration.
    To complete our configuration we must provide a name - the description is optional and can be used to describe what your configuration is all about.

    Check Configuration properties                         filled
    When you are done the dialog should look like this. Don't worry if you done something wrong the dialog will tell you.
    Press OK to return to the main configuration screen. The configuration you created should show up in the configuration table.
    You can go back to this dialog by selecting the configuration and pressing Properties...
    Our configuration is (of course) quite empty because we have not yet defined any checks.

  4. Select the configuration you created and press Configure... to open the Configuration Editor

    Checkstyle Configuration                         Editor
    In the left hand side tree all modules known to the plug-in are shown. These are all modules that come with Checkstyle out-of-the-box.
    The modules are semantically grouped into categories.
    The table on the right side shows the modules your configuration is actually containing.
    Based on the selection in the tree all modules in your configuration belonging to the selected group are shown.
    If you select a module in the tree or in the table a description of the module will be shown in the description area of the dialog.
    To add a particular module to your configuration you must select the module in the tree press the Add... button.
    For instance we open the first group Javadoc Comments and select the Method Javadoc module.
    Pressing the Add... button the property dialog for this module is shown.

    Checkstyle Module Editor
    Using the dialog you can customize the check for your needs.
    Mostly all modules have a severity combo box. With this you can specify if a violation of the check results in an error, warning or an info.
    The other settings in the editor are highly specific to the module. But don't bother for now, pressing OK will add the module to your configuration.
    The result should look like this:

    Checkstyle Configuration                         Editor filled
    Now your configuration contains the Method Javadoc check.
    Operating the enabled check box in the table lets you easily set the severity of the module to ignore.
    OK, now you figured it all out!
    Press OK to save your configuration and return to the main configuration page.
    In the main dialog press OK to store all changes you made.

  5. Go back to the project properties and select your configuration to be used to check your project

    Checkstyle Project                         Properties
    After you press OK your project will be rebuilt using your self created configuration.
    Look into the Eclipse Problems View again to see the effects. Now only Checkstyle warnings regarding missing or invalid method Javadoc should be there.

Congratulations!

Now we've covered all the basics of the Eclipse Checkstyle Plug-in.
Now you surely want to dive in and create an extensive configuration - trying out all checks that Checkstyle has to offer (which are a lot!).

Detailed information on the configuration options for each check can be found in the following sections: