intellij-sdk-code-samples/reference_guide/project_model/library.md

title
Library

A library is an archive of compiled code (such as JAR files) that your modules depend on.

The IntelliJ Platform supports three types of libraries:

• Module Library: the library classes are visible only in this module and the library information is recorded in the module .iml file.
• Project Library: the library classes are visible within the project and the library information is recorded under .idea/libraries directory or in the project .ipr file.
• Global Library: the library information is recorded in the applicationLibraries.xml file in <User Home>/.IntelliJIdea/config/options directory. Global libraries are similar to project libraries, but are visible for different projects.

For more information about libraries, refer to Libraries.

Accessing Libraries and Jars

Package libraries provides functionality for working with project libraries and jars.

How do I get a list of libraries a module depends on?

To get the list of libraries that a module depends on, use OrderEnumerator.forEachLibrary as follows.

final List<String> libraryNames = new ArrayList<String>();
ModuleRootManager.getInstance(module).orderEntries().forEachLibrary(library -> {
  libraryNames.add(library.getName());
  return true;
});
Messages.showInfoMessage(StringUtil.join(libraryNames, "\n"), "Libraries in Module");

This sample code outputs a list of libraries that the given module depends on.

How do I get a list of all libraries?

To manage the lists of application and project libraries, use LibraryTable. The list of application-level library tables is accessed by calling LibraryTablesRegistrar.getInstance().getLibraryTable(), whereas the list of project-level library tables is accessed through LibraryTablesRegistrar.getInstance().getLibraryTable(Project). Once you have a LibraryTable, you can get the libraries in it by calling LibraryTable.getLibraries().

To get the list of all module libraries defined in a given module, use the following API:

OrderEntryUtil.getModuleLibraries(ModuleRootManager.getInstance(module));

How do I get the library content?

Library provides the getUrls() method you can use to get a list of source roots and classes the library includes. To clarify, consider the following code snippet:

StringBuilder roots = new StringBuilder("The " + lib.getName() + " library includes:\n");
roots.append("Sources:\n");
for (String each : lib.getUrls(OrderRootType.SOURCES)) {
  roots.append(each).append("\n");
}
roots.append("Classes:\n");
for (String each : lib.getUrls(OrderRootType.CLASSES)) {
  strRoots.append(each).append("\n");
}
Messages.showInfoMessage(roots.toString(), "Library Info");

How do I create a library?

To create a library, you need to perform the following steps:

• Get a write action
• Obtain the library table to which you want to add the library. Use one of the following, depending on the library level:
  • LibraryTablesRegistrar.getInstance().getLibraryTable()
  • LibraryTablesRegistrar.getInstance().getLibraryTable(Project)
  • ModuleRootManager.getInstance(module).getModifiableModel().getModuleLibraryTable()
• Create the library by calling LibraryTable.createLibrary()
• Add contents to the library (see below)
• For a module-level library, commit the modifiable model returned by ModuleRootManager.getInstance(module).getModifiableModel().

For module-level libraries, you can also use simplified APIs in the ModuleRootModificationUtil class to add a library with a single API call. You can find an example of using these APIs in the sample plugin.

How do I add contents to a library or modify it?

To add or change the roots of a library, you need to perform the following steps:

• Get a write action
• Get a modifiable model for the library, using Library.getModifiableModel()
• Use methods such as Library.ModifiableModel.addRoot() to perform the necessary changes
• Commit the model using Library.ModifiableModel.commit().

How do I add a library dependency to a module?

Use ModuleRootModificationUtil.addDependency(module, library) from under a write action.

Checking Belonging to a Library

The ProjectFileIndex interface implements a number of methods you can use to check whether the specified file belongs to the project library classes or library sources. You can use the following methods:

• To check if a specified virtual file is a compiled class file use

  ProjectFileIndex.isLibraryClassFile(virtualFile)
  

• To check if a specified virtual file or directory belongs to library classes use

  ProjectFileIndex.isInLibraryClasses(virtualFileorDirectory)
  

• To check if the specified virtual file or directory belongs to library sources use

  ProjectFileIndex.isInLibrarySource(virtualFileorDirectory)
  

See the following code sample to see how the method mentioned above can be applied.

More details on libraries can be found in this code sample