W3cubDocs

/OpenJDK 25

Class SimpleJavaFileObject

java.lang.Object
javax.tools.SimpleJavaFileObject
All Implemented Interfaces:
FileObject, JavaFileObject
public class SimpleJavaFileObject extends Object implements JavaFileObject
Provides simple implementations for most methods in JavaFileObject. This class is designed to be subclassed and used as a basis for JavaFileObject implementations. Subclasses can override the implementation and specification of any method of this class as long as the general contract of JavaFileObject is obeyed.
Since:
1.6

Nested Class Summary

Nested classes/interfaces declared in interface JavaFileObject

JavaFileObject.Kind

Field Summary

Modifier and Type Field Description
protected final JavaFileObject.Kind kind
The kind of this file object.
protected final URI uri
A URI for this file object.

Constructor Summary

SimpleJavaFileObject(URI uri, JavaFileObject.Kind kind)
Modifier Constructor Description
protected
Construct a SimpleJavaFileObject of the given kind and with the given URI.

Method Summary

Modifier and Type Method Description
boolean delete()
Deletes this file object.
static JavaFileObject forSource(URI uri, String content)
Creates a JavaFileObject which represents the given source content.
Modifier getAccessLevel()
Provides a hint about the access level of the class represented by this file object.
CharSequence getCharContent(boolean ignoreEncodingErrors)
Returns the character content of this file object, if available.
JavaFileObject.Kind getKind()
Returns the kind of this file object.
long getLastModified()
Returns the time this file object was last modified.
String getName()
Returns a user-friendly name for this file object.
NestingKind getNestingKind()
Provides a hint about the nesting level of the class represented by this file object.
boolean isNameCompatible(String simpleName, JavaFileObject.Kind kind)
Checks if this file object is compatible with the specified simple name and kind.
InputStream openInputStream()
Returns an InputStream for this file object.
OutputStream openOutputStream()
Returns an OutputStream for this file object.
Reader openReader(boolean ignoreEncodingErrors)
Returns a reader for this object.
Writer openWriter()
Returns a Writer for this file object.
URI toUri()
Returns a URI identifying this file object.

Methods declared in class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

uri

protected final URI uri
A URI for this file object.

kind

protected final JavaFileObject.Kind kind
The kind of this file object.

Constructor Details

SimpleJavaFileObject

protected SimpleJavaFileObject(URI uri, JavaFileObject.Kind kind)
Construct a SimpleJavaFileObject of the given kind and with the given URI.
Parameters:
uri - the URI for this file object
kind - the kind of this file object

Method Details

toUri

public URI toUri()
Description copied from interface: FileObject
Returns a URI identifying this file object.
Specified by:
toUri in interface FileObject
Returns:
a URI

getName

public String getName()
Description copied from interface: FileObject
Returns a user-friendly name for this file object. The exact value returned is not specified but implementations should take care to preserve names as given by the user. For example, if the user writes the filename "BobsApp\Test.java" on the command line, this method should return "BobsApp\Test.java" whereas the toUri method might return file:///C:/Documents%20and%20Settings/UncleBob/BobsApp/Test.java.
Specified by:
getName in interface FileObject
Returns:
a user-friendly name

openInputStream

public InputStream openInputStream() throws IOException
Returns an InputStream for this file object.
Specified by:
openInputStream in interface FileObject
Implementation Requirements:
This implementation always throws UnsupportedOperationException.
Returns:
an InputStream
Throws:
IOException - if an I/O error occurred

openOutputStream

public OutputStream openOutputStream() throws IOException
Returns an OutputStream for this file object.
Specified by:
openOutputStream in interface FileObject
Implementation Requirements:
This implementation always throws UnsupportedOperationException.
Returns:
an OutputStream
Throws:
IOException - if an I/O error occurred

openReader

public Reader openReader(boolean ignoreEncodingErrors) throws IOException
Returns a reader for this object. The returned reader will replace bytes that cannot be decoded with the default translation character. In addition, the reader may report a diagnostic unless ignoreEncodingErrors is true.
Specified by:
openReader in interface FileObject
Implementation Requirements:
This implementation wraps the result of getCharContent(boolean) in a Reader.
Parameters:
ignoreEncodingErrors - ignore encoding errors if true
Returns:
a Reader wrapping the result of getCharContent
Throws:
IllegalStateException - if this file object was opened for writing and does not support reading
UnsupportedOperationException - if this kind of file object does not support character access
IOException - if an I/O error occurred

getCharContent

public CharSequence getCharContent(boolean ignoreEncodingErrors) throws IOException
Returns the character content of this file object, if available. Any byte that cannot be decoded will be replaced by the default translation character. In addition, a diagnostic may be reported unless ignoreEncodingErrors is true.
Specified by:
getCharContent in interface FileObject
Implementation Requirements:
This implementation always throws UnsupportedOperationException.
Parameters:
ignoreEncodingErrors - ignore encoding errors if true
Returns:
a CharSequence if available; null otherwise
Throws:
IOException - if an I/O error occurred

openWriter

public Writer openWriter() throws IOException
Returns a Writer for this file object.
Specified by:
openWriter in interface FileObject
Implementation Requirements:
This implementation wraps the result of openOutputStream() in a Writer.
Returns:
a Writer wrapping the result of openOutputStream
Throws:
IllegalStateException - if this file object was opened for reading and does not support writing
UnsupportedOperationException - if this kind of file object does not support character access
IOException - if an I/O error occurred

getLastModified

public long getLastModified()
Returns the time this file object was last modified. The time is measured in milliseconds since the epoch (00:00:00 GMT, January 1, 1970).
Specified by:
getLastModified in interface FileObject
Implementation Requirements:
This implementation returns 0L.
Returns:
0L

delete

public boolean delete()
Deletes this file object. In case of errors, returns false.
Specified by:
delete in interface FileObject
Implementation Requirements:
This implementation does nothing.
Returns:
false

getKind

public JavaFileObject.Kind getKind()
Description copied from interface: JavaFileObject
Returns the kind of this file object.
Specified by:
getKind in interface JavaFileObject
Returns:
this.kind

isNameCompatible

public boolean isNameCompatible(String simpleName, JavaFileObject.Kind kind)
Checks if this file object is compatible with the specified simple name and kind. A simple name is a single identifier (not qualified) as defined in The Java Language Specification, section 6.2.
Specified by:
isNameCompatible in interface JavaFileObject
Implementation Requirements:
This implementation compares the path of its URI to the given simple name. This method returns true if the given kind is equal to the kind of this object, and if the path is equal to simpleName + kind.extension or if it ends with "/" + simpleName + kind.extension.

This method calls getKind() and toUri() and does not access the fields uri and kind directly.

Parameters:
simpleName - a simple name of a class
kind - a kind
Returns:
true if this file object is compatible; false otherwise

getNestingKind

public NestingKind getNestingKind()
Provides a hint about the nesting level of the class represented by this file object. This method may return NestingKind.MEMBER to mean NestingKind.LOCAL or NestingKind.ANONYMOUS. If the nesting level is not known or this file object does not represent a class file this method returns null.
Specified by:
getNestingKind in interface JavaFileObject
Implementation Requirements:
This implementation returns null.
Returns:
the nesting kind, or null if the nesting kind is not known

getAccessLevel

public Modifier getAccessLevel()
Provides a hint about the access level of the class represented by this file object. If the access level is not known or this file object does not represent a class file this method returns null.
Specified by:
getAccessLevel in interface JavaFileObject
Implementation Requirements:
This implementation returns null.
Returns:
the access level

forSource

public static JavaFileObject forSource(URI uri, String content)
Creates a JavaFileObject which represents the given source content.

The provided uri will be returned from toUri(). The provided content will be returned from getCharContent(boolean). The getKind() method will return JavaFileObject.Kind.SOURCE.

All other methods will behave as described in the documentation in this class, as if the constructor is called with uri and Kind.SOURCE.

This method can be, for example, used to compile an in-memory String to a set of classfile in a target directory: 

     var code = """
                public class CompiledCode {}
                """;
     var compiler = ToolProvider.getSystemJavaCompiler();
     var targetDirectory = "...";
     var task = compiler.getTask(null,
                                 null,
                                 null,
                                 List.of("-d", targetDirectory),
                                 null,
                                 List.of(SimpleJavaFileObject.forSource(URI.create("CompiledCode.java"), code)));
     if (!task.call()) {
         throw new IllegalStateException("Compilation failed!");
     }
Parameters:
uri - that should be used for the resulting JavaFileObject
content - the content of the JavaFileObject
Returns:
a JavaFileObject representing the given source content.
Since:
23

© 1993, 2025, Oracle and/or its affiliates. All rights reserved.
Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
https://docs.oracle.com/en/java/javase/25/docs/api/java.compiler/javax/tools/SimpleJavaFileObject.html