Defines the implementation of the system Java compiler and its command line equivalent, javac.

The com.sun.source.* packages provide the Compiler Tree API: an API for accessing the abstract trees (ASTs) representing Java source code and documentation comments, used by javac, javadoc and related tools.

javac

This module provides the equivalent of command-line access to javac via the ToolProvider and Tool service provider interfaces (SPIs), and more flexible access via the JavaCompiler SPI.

Instances of the tools can be obtained by calling ToolProvider.findFirst or the service loader with the name "javac".

In addition, instances of JavaCompiler.CompilationTask obtained from JavaCompiler can be downcast to JavacTask for access to lower level aspects of javac, such as the Abstract Syntax Tree (AST).

This module uses the FileSystemProvider API to locate file system providers. In particular, this means that a jar file system provider, such as that in the jdk.zipfs module, must be available if the compiler is to be able to read JAR files.

Options and Environment Variables

The full set of options and environment variables supported by javac is given in the javac Tool Guide. However, there are some restrictions when the compiler is invoked through its API.

• The -J option is not supported. Any necessary VM options must be set in the VM used to invoke the API. IllegalArgumentException will be thrown if the option is used when invoking the tool through the JavaCompiler API; an error will be reported if the option is used when invoking javac through the ToolProvider or legacy Main API.

• The "classpath wildcard" feature is not supported. The feature is only supported by the native launcher. When invoking the tool through its API, all necessary jar files should be included directly in the --class-path option, or the CLASSPATH environment variable. When invoking the tool through its API, all components of the class path will be taken literally, and will be ignored if there is no matching directory or file. The -Xlint:paths option can be used to generate warnings about missing components.

The following restrictions apply when invoking the compiler through the JavaCompiler interface.

• Argument files (so-called @-files) are not supported. The content of any such files should be included directly in the list of options provided when invoking the tool though this API. IllegalArgumentException will be thrown if the option is used when invoking the tool through this API.

• The environment variable JDK_JAVAC_OPTIONS is not supported. Any options defined in the environment variable should be included directly in the list of options provided when invoking the API; any values in the environment variable will be ignored.

• Options that are just used to obtain information (such as --help, --help-extended, --version and --full-version) are not supported. IllegalArgumentException will be thrown if any of these options are used when invoking the tool through this API.

• Path-related options depend on the file manager being used when calling JavaCompiler.getTask(java.io.Writer, javax.tools.JavaFileManager, javax.tools.DiagnosticListener<? super javax.tools.JavaFileObject>, java.lang.Iterable<java.lang.String>, java.lang.Iterable<java.lang.String>, java.lang.Iterable<? extends javax.tools.JavaFileObject>). The "standard" options, such as --class-path, --module-path, and so on are available when using the default file manager, or one derived from it. These options may not be available and different options may be available, when using a different file manager. IllegalArgumentException will be thrown if any option that is unknown to the tool or the file manager is used when invoking the tool through this API.

Note that the CLASSPATH environment variable is honored when invoking the compiler through its API, although such use is discouraged. An environment variable cannot be unset once a VM has been started, and so it is recommended to ensure that the environment variable is not set when starting a VM that will be used to invoke the compiler. However, if a value has been set, any such value can be overridden by using the --class-path option when invoking the compiler, or setting StandardLocation.CLASS_PATH in the file manager when invoking the compiler through the JavaCompiler interface.

SuppressWarnings

JLS 9.6.4.5 specifies a number of strings that can be used to suppress warnings that may be generated by a Java compiler. In addition, javac also supports other strings that can be used to suppress other kinds of warnings. The following table lists all the strings that can be used with @SuppressWarnings.

Strings supported by SuppressWarnings

String	Suppress Warnings About ...
auxiliaryclass	an auxiliary class that is hidden in a source file, and is used from other files
cast	use of unnecessary casts
classfile	issues related to classfile contents
deprecation	use of deprecated items
dep-ann	items marked as deprecated in a documentation comment but not using the @Deprecated annotation
divzero	division by constant integer 0
empty	empty statement after if
exports	issues regarding module exports
fallthrough	falling through from one case of a switch statement to the next
finally	finally clauses that do not terminate normally
lossy-conversions	possible lossy conversions in compound assignment
missing-explicit-ctor	missing explicit constructors in public and protected classes in exported packages
module	module system related issues
opens	issues regarding module opens
overloads	issues regarding method overloads
overrides	issues regarding method overrides
path	invalid path elements on the command line
preview	use of preview language features
rawtypes	use of raw types
removal	use of API that has been marked for removal
requires-automatic	use of automatic modules in the requires clauses
requires-transitive-automatic	automatic modules in requires transitive
serial	Serializable classes that do not have a serialVersionUID field, or other suspect declarations in Serializable and Externalizable classes and interfaces
static	accessing a static member using an instance
strictfp	unnecessary use of the strictfp modifier
synchronization	synchronization attempts on instances of value-based classes
text-blocks	inconsistent white space characters in text block indentation
this-escape	superclass constructor leaking this before subclass initialized
try	issues relating to use of try blocks (that is, try-with-resources)
unchecked	unchecked operations
varargs	potentially unsafe vararg methods
doclint:accessibility	accessibility issues found in documentation comments
doclint:all	all issues found in documentation comments
doclint:html	HTML issues found in documentation comments
doclint:missing	missing items in documentation comments
doclint:reference	reference issues found in documentation comments
doclint:syntax	syntax issues found in documentation comments