This is the developer-oriented FAQ for NetBeans IDE 4.x, 5.x, 6.x, 7.x and 8.x. Developer in this context means "person writing NetBeans extension modules (plug-ins), or applications based on the NetBeans Platform". Don't see your developer-oriented question here? Ask on firstname.lastname@example.org (subscribe to post). Not writing modules? See the list of other FAQs.
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- What is a module?
- Becoming a proficient module developer
- How do I get sources for NetBeans using Mercurial (hg)?
- How do I get zipped sources for a periodic build?
- What API do I want to use for x, y or z?
- I have fixed a bug in NetBeans. Can I contribute the patch?
- I have written a module. Can I sell it?
- Why are some packages org.netbeans.api.something and others are org.netbeans.something.api?
- What is netbeans.exe, who compiles it and why is it there?
- How do I get commit access to NetBeans source repository?
- Where can I find Javadoc for the IDE and Platform?
- Where is the Platform and how can I build it?
- How do I set up a NetBeans Platform in the IDE?
- There sure are a lot of modules in the source tree. What are they for?
- In the Libraries tab of my application's Project Properties, there sure are a lot of modules listed. What are they for?
Tutorials and important starting points
- What are the basic things I should know about NetBeans' architecture to get started creating NetBeans Platform applications?
- Any tutorials out there, please?
- NetBeans API starting point
- NetBeans Annotation Cheat Sheet
Getting support, where to find examples
- NetBeans mailing lists - get help from experts all around the globe
- Search the support list for module developers
- Search the NetBeans development mailing list
- Filing a bug report
- Examples of how to use various APIs
- Browse Samples Online
- Where can I find more documentation on certain APIs?
- Consider all of these support options
- Can I get training material for the NetBeans Certification course?
Application Lifecycle and Hooks
Development issues, module basics and classpath issues, and information about RCP/Platform application configuration
- My module uses some libraries. I've tried setting CLASSPATH but it doesn't work. Help!
- How do module dependencies/classloading work?
- How do I have two source directories within one module?
- What classloaders are created by the module system?
- Why can't I load properties using UIDefaults?
- I need to package some third party libraries with my module. How do I do that?
- What is an "NBM"?
- Can I sign NBMs I create?
- What is an SPI? How is it different from an API?
- My module requires JDK 6 - how do I keep it from being loaded on an older release?
- What is a library wrapper module and how do I use it?
- When should I use a library wrapper module and when should I just package the library into my module?
- How to store external libraries in the NetBeans Hg repository
- How do I add native libraries?
- What is an implementation dependency and what/how/when should I use one?
- My module uses class XYZ from NetBeans' APIs. It compiles, but I get a NoClassDefFoundError at runtime. Why?
- What is a module cluster?
- What is the difference between a suite and a cluster?
- How can I reuse my modules in several RCP applications?
- Can I use modules from update center in my RCP application?
- My project.xml lists more dependencies than I really need. How can I fix it?
- Can I work on just one or two modules from the NetBeans source base by themselves?
- Is there a standard way to provide user documentation (help) for my module?
- Where is TopManager? I'm trying to do the examples from the O'Reilly book
- There is a class under org.netbeans.core that does what I need. Can I depend on it?
- Common calls that should be done slightly differently in NetBeans than standard Swing apps (loading images, localized strings, showing dialogs)
- How do I create a patch for a preexisting NetBeans module?
- I want to use one version of the Platform with another version of the build harness. Can I?
- I am developing a NetBeans module. What performance criteria should it satisfy?
- I want to set some flags or CLI arguments for running my NB RCP/Platform based application (such as disable assertions). How do I do that?
- How can I fix memory leaks?
- How to run module with more PermGen and Heap memory?
- What is a WeakListener?
- When should I use a WeakListener?
- How can I profile NetBeans?
- Can I test changes to the IDE without going through the license check and so on?
- How can I customize the build process?
- How can I customize the default project directory for my application, replacing "NetBeansProjects"?
- Migrating to a newer version of the Platform
- How can I launch an Ant Task on all modules of my suite?
- Do I need to restart NetBeans every time to debug new changes?
- How can I have my application compiled in a specific version of the platform?
- How do I develop and debug annotations for NetBeans platform apps?
- See also plugin documentation
- How can I create localization modules using Maven?
- Why can't I use system scope for a library wrapper module?
- Can I use JRebel to speed up development?
- How to convert an ANT-based NetBeans Module to a Maven-based NetBeans Module?
Configuration: How Modules Install Things
- What are the ways a module can influence the system?
- What is the "default Lookup"?
- How do I run some code when my module starts/loads/unloads?
- What is an XML layer?
- What is the system filesystem?
- How can I see the filesystem?
- What are .instance files?
- What are .settings files?
- What are .shadow files?
- What is the user directory, what is in it, and why do I need one?
- How do I specify the order for my menu items/toolbar buttons/files in the system filesystem?
- Can I dynamically change the contents of the System Filesystem at runtime?
- Can I bundle some additional files with my module? If so, how can I find those files to use them from my module?
When There Are Multiple Ways To Do Something...
- Installing things declaratively vs. installing things programmatically
- I need to register some object to be found at runtime, or run some code on startup. Which way should I use?
- Which way should I register an object in the default Lookup?
- Should I register an object in my layer file using .instance or .settings files? What about .shadow files?
Actions: How to add things to Files, Folders, Menus, Toolbars and more
- How do I add an action to the main menu?
- How do I add an action to a toolbar in the main window?
- How do I add a toggle-able action to the toolbar/main menu?
- How do I add an action to the toolbar of the editor?
- How do I make an action that is automatically enabled/disabled depending on what's selected?
- How do I make a checkable/toggle-able action that represents a preference option?
- What is the Actions folder in the system filesystem, and why should I use it?
- How do I add an action (incl. shortcut) at runtime?
- How do I add an action to all files of a given mime-type?
- How do I add an action to the context menu of a specific editor?
- How do I add an action to the context menu of all editors?
- How do I add an action to a project popup menu?
- How do I add an action to a project popup menu of a specific project type?
- How do I add an action to a project popup menu of my own project type?
- How do I add an action to a folder?
- How do I add an action to any folder?
- How do I add an action to an Java package?
- How do I add an action to the tools menu?
- How do I add an action to my custom node?
- How do I make my Node have a submenu on its popup menu?
- How do I add an action to the global popup menu of tabs?
- How do I add a dropdown menu to toolbar?
- How do I add a dropdown menu to toolbar that is selectively enabled/disabled?
- How do I hide/remove default toolbar buttons and/or menu items?
- How do I hide/show toolbar dynamically?
- Some module in the IDE etc. already has a menu item I like, but I just want to rename it. Can I?
- Can I change the contents of a menu according to the selected file in the editor, or hide or show a whole menu?
- Can I install submenus into popups or other menus, instead of a regular action?
- How do i change the closing action of the MainWindow?
- How do I get the Open File item on the File menu into my platform application?
- Looking at the UI how do I find a module that implements a menu item
- How can I add a JSeparator to the main toolbar?
- How do I remove Menu Item, Toolbar Button from plug-in's XML Layer?
- How do I have only Shortcut Keys for an Action?
- How do I change the appearance of the menu items and toolbar buttons for my Action
- How do I invoke the IDE-Log upon Startup?
- Which NetBeans Platform Action Class Should I Use?
- How to Make the NetBeans Platform Sensitive to Customers
- How do I add content to the Global Context?
- How do I add an icon to the context menu?
- How do I add an action to the context menu of the members or hierarchy view?
- How do I invoke an action programmatically?
- How can I reuse and/or organise actions only by using annotations (@ActionReferences)?
- How can I fix "WARNING [org.openide.util.Utilities]: findContextMenuImpl, getPopupPresenter returning null for" when using a PopupPresenter ?
- How do I define and localise the keymap category of an action?
- How do I create an action which can be invoked by a macro?
- How do key bindings work?
- Binding one key to more than one action
- Why should I use D- for Ctrl and O- for Alt? I thought C- stood for Ctrl and A- stood for Alt!
- I want my action to appear between two existing items/in a specific place in the menu. Can I do that?
- What about editor-specific keybindings?
- Which keybindings are already being used?
- How do I add default shortcuts for SystemActions (like cut, paste, etc)?
- How to get the shortcut/shortkey of an action at runtime?
- How to set the shortcut of an action outside of your own module?
- What is a Lookup?
- What uses Lookup?
- Why use Lookup - wouldn't a Map be good enough?
- How do I use Java generics with Lookup?
- What is the "default Lookup"?
- How can I override an instance in the Lookup?
- What is the difference between getCookie(Class), SharedClassObject.findObject(Class) and Lookup.lookup(Class)?
- How do I implement my own lookup or proxy another one?
- If there is more than one of a type in a Lookup, which instance will I get?
- How can I find out what is in a Lookup
- How can I add support for lookups on nodes representing my file type?
- When should I use Lookup in my own APIs?
- After adding my class to Lookup I get a "ClassNotFoundException" when trying to look it up, why?
- Event Bus in NetBeans
- How do I lazy-load an item in the lookup?
- Register instances via custom annotations
- How can I register services into the lookup using the system filesystem?
Files and Data Objects
- How does NetBeans recognize files?
- What is a FileObject?
- What is a FileSystem?
- What are file attributes?
- What is a DataObject?
- What is a DataLoader?
- How can I be notified when a file is modified and saved?
- How can I be notified when a file is opened?
- How do I add a menu item to the popup menu of every folder in the system?
- Can I add a menu item to the context menu of every Java source file?
- I'm having trouble implementing this filesystem....
- How do I add support for an XML type with a different extension?
- The next button is never enabled when I create my DataObject from a template. Help!
- How can I create a FileObject in memory?
- How can I create declarative MIMEResolver and add new file type?
- I am listening for changes in a folder/file but when there are changes I do not receive an event
- I want to listen for changes in a file that may not exist or may be deleted and re-created
- I need to show a file chooser. How can I remember most-recently-used directories?
Converting between common data types and finding things
- FileObjects versus Files
- URIs and URLs
- How do I get a java.io.File for a FileObject?
- How do I get a FileObject for a File?
- How do I get a DataObject for a FileObject?
- How do I get a FileObject for a DataObject?
- How do I get a Node for a DataObject?
- How do I get a DataObject for a Node?
- How do I get a reference to the system filesystem?
- I have a .instance file. How do I get an actual object instance?
- I have a folder full of .instance files. How do I get any/all of the object instances?
Editor and Edited Files
- How can I get a list of open editors/documents?
- How can I get the currently open document in the selected editor?
- How can I track what file the user is currently editing?
- How can I get the position of the caret/line in the selected editor?
- How can I open a file in the editor in read-only mode?
- How can I open a file in the editor at a particular line number and column?
- How to get mime type from Document or JTextComponent?
- Is it safe to programmatically modify a file which is open in the editor?
- I want to make some programmatic changes to the edited file. How can I do it so one Undo undoes it all?
- Can I add syntax coloring for my own data object/MIME type?
- How to add code completion to any JEditorPane
- What is MimePath?
- What is MimeLookup?
- How is MimeLookup composed?
- How can I create JEditorPane for a specific document type?
- Project Encoding vs. File Encoding - What are the precedence rules used in NetBeans 6.0?
- I want to add annotations to my editor, for errors, or other reasons. How?
- Can I add a menu item to the context menu of the Java source editor?
- How to use the diff view in my own application/plugin?
- How to reuse XML syntax highlighting in your own editor
- How to add code templates?
File Management (within the IDE/Application)
- I want my module to disable some of the modules that would normally be enabled. Possible?
- How do I debug a module I'm building?
- Can I disable Auto Update (for example, while running tests)?
- How can I change the NetBeans splash screen shown when an installed module requires restart?
- How can I obfuscate a module?
- Why am I getting a ClassCastException when the class is clearly of the right type?
- Can two or more modules contain the same package?
- Can I create a console or server (non-GUI) app with the NetBeans Platform?
- How can code in one module be notified when other modules are loaded or unloaded?
- What is an autoload module?
- How fix module dependencies automatically?
Nodes and Explorer
- What is a Node?
- What is "explorer"?
- What is an ExplorerManager?
- What is an Explorer View?
- How do I show a Node in my explorer view?
- I need to create my own Nodes. What should I subclass?
- How to serialize my nodes?
- I need to show Nodes for objects that are slow to create. How do I compute Node children on a background thread?
- How do I create a TopComponent (tab in the main window) to show some Nodes?
- I have a reference to an existing Node from some other module. Can I add cookies/properties/children?
- Can I add, remove or reorder children of a node on the fly?
- How do I make a particular node visible in the Explorer, and maybe select it?
- How do I get at the file that a particular node represents?
- Tracking selections in the Explorer
- I need to add to/remove from/customize the content of my Node/DataObject/TopComponent's Lookup. How do I do it?
- I need to write some code that tracks the global selection. What should I do?
- How do I "decorate" nodes that come from another module (i.e. add icons, actions)?
- How do I preserve the column attributes of a TreeTableView?
- How do I remove the "..." buttons of a TreeTableView?
- How can I make sortable columns in a TreeTableView?
- How can I add a "View" capability for data my node represents?
- How can I implement "Select all/Deselect all/Invert selection" features?
- Why do my nodes in the Explorer always have an expand-box by them, even though they have no children?
- How can I prevent (or override) the node deletion dialog?
- How can I change my node's appearance?
- How do I handle cut, copy and paste?
- How can I graphically create a ChoiceView?
- How can I design explorer views in Mantisse GUI editor?
- I have a Node.Property for a file. How can I control the file chooser that is the custom editor?
- I have a Node.Property. I want to control its appearance or custom editor somehow. Can I do that without writing my own property editor?
- I want to allow other modules to inject objects into my Node's Lookup, or Actions into its actions
- How can I add horizontal scrolling support to the OutlineView component?
Tasks and Progressbar
- How to use the Progress API?
- Cancellable Tasks and Progress Indicators
- How to execute a long running task from an action without blocking the GUI?
- How to run/execute an external program?
Command Line Parsing
- Can something that the user sets on the command line determine whether a menu item is enabled?
- Same as the above, but this time for enabling/disabling modules?
- How to pass command line arguments to a NetBeans Platform application when run inside the IDE
- Platform parsing command line arguments
- What is a background thread and why do I need one?
- I need to run some code on a background thread. Can the platform help me?
- When should I use RequestProcessor.getDefault() and when should I create my own RequestProcessor?
- What APIs come with built-in background thread handling?
- How can I run an operation occasionally on a background thread, but reschedule it if something happens to delay it?
Creating a Custom Programming Language
- How do I add syntax highlighting for my language?
- How can I create a custom Debugger for my language?
- How do I let the user set preferences/options/customization/configuration for my module/application?
- Can I add new panels to the Options window?
- How to register options for export/import to module's layer?
- How do I change the application's Java start parameters?
- How can I configure my options panel to be found by global quicksearch or options search?
- How do you open the option dialog with a preselected category?
- How do you change the configuration of other modules?
- What is the window system
- What are Modes?
- What are TopComponents?
- How do I use Matisse/GroupLayout (new form editor/layout manager in 5.0) in my windowing system components
- I want to show my own component(s) in the main window - where do I start?
- Windows and dialogs
- How does the XML API for installing window system components work?
- How do I use .wstcrf/.wsmode/.settings files to install my module's components in the window system?
- My TopComponent always opens in the editor area, but I want it to open in the same place as XYZ
- Why does TopComponent have a getLookup() method? What is it for?
- I want to disable the popup menu on the toolbars in the main window. How do I do that?
- How can I change the executable's icon?
- How does the window system really work?
- How can I replace the Window System?
- How do I set the initial size of the main window?
- Secrets of the NetBeans Window System
- I want to create a TopComponent class to use as an editor, not a singleton
- How can I change my TopComponent to not be a singleton?
- I have a non-singleton TopComponent. Can I write actions which show all available instances in the main menu?
- Which TopComponents are open?
- How to override the default size of an existing window?
- How to create a custom window mode?
- How to change main title contents?
- How can I customize the window system via the latest 7.1 techniques/enhancements?
- How to mix lightweight (Swing) and heavyweight (AWT) components?
- How to maximize a TopComponent?
XML Multiview API
- How do I get started with the XML Multiview API? (Part 1)
- How do I get started with the XML Multiview API? (Part 2)
- How do I get started with the XML Multiview API? (Part 3)
- How do I get started with the XML Multiview API? (Part 4)
- How do I get started with the XML Multiview API? (Part 5)
- How do I get started with the XML Multiview API? (Part 6)
- How do I get started with the XML Multiview API? (Part 7)
- How to change selected tab of Multiview?
- How can I open a Project programatically?
- How to get the project of the active file in the editor?
- How to get the name or icon of a project?
- How to get the name of the active project group?
- How to listen for projects to be opened/closed?
- Is it possible to extend an existing project type?
- How to add a new panel to a Project Properties dialog?
- How do I add an action to a project popup menu?
- How do I add an action to a project popup menu of a specific project type?
- How do I identify the "main project"?
- How do I register a "ProjectCustomizer" to multiple project types?
- How determine all available project types?
- How can I define the available File types when the user right-clicks the project folder and chooses "New"?
Wizards and Templates
- How do I make a file template which actually creates a set of files at once?
- I am creating a non-IDE application. How do I enable/control templates?
- How do I get started using FreeMarker to generate my templates? (and this plugin might help too)
- How do I show that a user has filled an invalid input into my wizard?
- How to open files in editor after project creation?
- How to customize the button text of default buttons of a wizard (Finish, Cancel, etc.)?
Properties and PropertySheet
- How do I change the default behavior of PropertySheet editors?
- How do I show my node's properties in the Properties view?
- How do I display different groups of properties on buttons in the property sheet the way Matisse does?
- How do I color the cells in a property sheet?
- How do I display an icon in my property sheet?
- How do I hide the description area in property window?
- How do I add a readonly property?
- How do I create my own tab in the output window and write to it?
- How do I route the output from an external process to the output window?
- How to implement custom IOProvider?
- How do I embed output window tab to another component?
- How to use color text in Output Window?
- How to get user input in the Output Window?
Using Enterprise Resources from NetBeans module
- Java EE Application Client on top of NetBeans Platform Tutorial
- How to call EJB from NetBeans module
Running and Writing tests
- Using NbModuleSuite & friends
- Running tests on a platform application
- Typical Test Patterns
- NetBeans Developer Test FAQ
- Testing things that use FileObjects
- Writing Tests for DataObjects and DataLoaders
- How do I test something which uses the System Filesystem?
Branding your application
- Branding About Dialog
- Branding Updater Splash
- How do I set the version number?
- How do I remove the status bar?
- Translating a NetBeans Module
Authentication and Authorization in Platform Apps
- Building a Login Screen for a NetBeans Platform Application: Part 1, Part 2 and Part 3
- Other strategies for authentication and authorization
Logging and Error Handling
- Using java.util.logging in NetBeans
- UI Logging through Gestures Collector
- How can I suppress the Unexpected Exception dialog?
- How can I customize the Unexpected Exception dialog?
- How can I add a timestamp to the logs?
- JavaHelp integration guide
- How do I fix problems about 'ide.welcome'?
- How do I change the default help topic?
- How do I remove the helpset?
- How do I connect ui to JavaHelp?
- Why doesn't my JavaHelp content show up?
- How can I hook up JavaHelp to property sets or individual properties?
- How can I override JavaHelp to display my own custom help or documentation?
Look and Design
- How can I set the Swing look and feel on startup?
- I have a custom component. How can I make it respond to --fontsize like the rest of NetBeans?
- How to provide non-inverted images for dark LookAndFeels like DarkMetal/Darcula?
Deploying Changes through AutoUpdate and using Autoupdate API
- How can I use AutoUpdate to deploy updates and new modules for my application?
- How can I update the splash screen, title bar and other branding items via AutoUpdate?
- How can I set the interval at which AutoUpdate checks its servers?
- How can I find Javadoc of Autoupdate API with hints to use it?
- What other documentation is available about AutoUpdate?
- How to specify post-install code in NBM?
- How can I run the installer for something else during module installation? (since NB6.5)
- How to update NetBeans Platform Application silently?
- How to deal with pack200 compression in NBM? (since NB6.9)
- How to force to check for updates at every startup?
- How to change the update center URL via code?
Deployment using installers / NBI
Programmatic access to Java Sources
The following applies only to NetBeans 6.0 and later.
- How do I Get All Methods/Fields/Constructors of a Class?
- How can I programmatically modify a Java source file?
- How to obtain a source file for a Java class and open in the editor?
- How can I scan a classpath to find all classes of a particular type?
- See Java_DevelopersGuide for more specific FAQ entries
When things go wrong: Troubleshooting
- I've got a class not found error/exception. How can I fix it?
- I find files missing from the source ZIP file
- NetBeans Platform and 3rd party components
- Where to download sources of MPL third-party components?
- Where to download sources of LGPL third-party components?
- Where to download sources of EPL third-party components?
- What is the Contributor Agreement ("CA")?
- Do I have to fill out a CA?
- How do I file a completed CA?
- Can I file my completed CA by e-mail?
- I've already signed a JCA; do I still have to sign the CA?
- I've already signed a CA for another Oracle project, do I need to sign another one for NetBeans?
- I've already signed a recent version of the CA, do I need to sign the newest version?
- Do I have to file a CA for every contribution?
- Once I have a CA on file, can I change my mind and cancel?
- I tried to make a contribution to netbeans.org and signed a CA, but my contribution was not accepted. What is the result?
- Why does NetBeans request a CA?
- I have a CA or JCA on file and I have made a code contribution to netbeans.org. Can I get listed on the copyright notice?
- If my company wants me to contribute changes, who should sign the CA, me or my company?
- Can my company sign a blanket JCA for all its employees?