Most commonly, a virtual file is a file in a local file system. However, the IntelliJ Platform supports multiple pluggable file system implementations, so virtual files can also represent classes in a JAR file, old revisions of files loaded from a version control repository, and so on.
The VFS level deals only with binary content. Contents of a
VirtualFile are treated as a stream of bytes, but concepts like encodings and line separators are handled on higher system levels.
How do I get a virtual file?
Local File System Path
What can I do with it?
Typical file operations are available, such as traverse the file system, get file contents, rename, move, or delete. Recursive iteration should be performed using
VfsUtilCore.iterateChildrenRecursively() to prevent endless loops caused by recursive symlinks.
Where does it come from?
The VFS is built incrementally by scanning the file system up and down, starting from the project root. VFS refresh operations detect new files appearing in the file system. A refresh operation can be initiated programmatically using
VirtualFile.refresh(). VFS refreshes are also triggered whenever file system watchers receive file system change notifications.
Invoking a VFS refresh might be necessary for accessing a file that has just been created by an external tool through the IntelliJ Platform APIs.
How long does a virtual file persist?
A particular file on disk is represented by equal
VirtualFile instances for the IDE process's entire lifetime. There may be several instances corresponding to the same file, and they can be garbage-collected. The file is a
UserDataHolder, and the user data is shared between those equal instances. If a file is deleted, its corresponding
VirtualFile instance becomes invalid (
false), and operations cause exceptions.
How do I create a virtual file?
Usually, you don't. As a general rule, files are created either through the PSI API or through the regular
If one needs to create a file through VFS, use
VirtualFile.createChildData() to create a
VirtualFile instance and
VirtualFile.setBinaryContent() to write some data to the file.
How do I get notified when VFS changes?
For a non-blocking alternative, starting with version 2019.2 of the platform, see
Are there any utilities for analyzing and manipulating virtual files?
For storing a large set of Virtual Files, use dedicated
ProjectLocator to find the projects that contain a given virtual file.
How do I extend VFS?
To provide an alternative file system implementation (for example, an FTP file system), implement the
VirtualFileSystem class (most likely you'll also need to implement
VirtualFile), and register your implementation via
com.intellij.virtualFileSystem extension point (2019.2 and later) or application component for earlier versions.
To hook into operations performed in the local file system (for example, when developing a version control system integration that needs custom rename/move handling), implement
LocalFileOperationsHandler and register it via
What are the rules for working with VFS?
See Virtual File System for a detailed description of the VFS architecture and usage guidelines.