Provided by: aspectj_1.9.2-1_all 
NAME
ajc — compiler and bytecode weaver for the AspectJ and Java languages
SYNOPSIS
ajc [Options] [file... | @file... | -argfile file... ]
Description
The ajc command compiles and weaves AspectJ and Java source and .class files, producing .class files
compliant with any Java VM (1.1 or later). It combines compilation and bytecode weaving and supports
incremental builds; you can also weave bytecode at run-time using "" >.
The arguments after the options specify the source file(s) to compile. To specify source classes, use
-inpath (below). Files may be listed directly on the command line or in a file. The -argfile file and
@file forms are equivalent, and are interpreted as meaning all the arguments listed in the specified
file.
Note: You must explicitly pass ajc all necessary sources. Be sure to include the source not only for the
aspects or pointcuts but also for any affected types. Specifying all sources is necessary because,
unlike javac, ajc does not search the sourcepath for classes. (For a discussion of what affected types
might be required, see The AspectJ Programming Guide, Implementation Appendix
../progguide/implementation.html) .
To specify sources, you can list source files as arguments or use the options -sourceroots or -inpath.
If there are multiple sources for any type, the result is undefined since ajc has no way to determine
which source is correct. (This happens most often when users include the destination directory on the
inpath and rebuild.)
Options
-injars JarList
deprecated: since 1.2, use -inpath, which also takes directories.
-inpath Path
Accept as source bytecode any .class files in the The output will include these classes,
possibly as woven with any applicable aspects. Path is a single argument containing a list of
paths to zip files or directories, delimited by the platform-specific path delimiter.
-aspectpath Path
Weave binary aspects from jar files and directories on path into all sources. The aspects
should have been output by the same version of the compiler. When running the output classes,
the run classpath should contain all aspectpath entries. Path, like classpath, is a single
argument containing a list of paths to jar files, delimited by the platform- specific classpath
delimiter.
-argfile File
The file contains a line-delimited list of arguments. Each line in the file should contain one
option, filename, or argument string (e.g., a classpath or inpath). Arguments read from the
file are inserted into the argument list for the command. Relative paths in the file are
calculated from the directory containing the file (not the current working directory).
Comments, as in Java, start with // and extend to the end of the line. Options specified in
argument files may override rather than extending existing option values, so avoid specifying
options like -classpath in argument files unlike the argument file is the only build
specification. The form @file is the same as specifying -argfile file.
-outjar output.jar
Put output classes in zip file output.jar.
-outxml Generate aop.xml file for load-time weaving with default name.
-outxmlfile custom/aop.xml
Generate aop.xml file for load-time weaving with custom name.
-incremental
Run the compiler continuously. After the initial compilation, the compiler will wait to
recompile until it reads a newline from the standard input, and will quit when it reads a 'q'.
It will only recompile necessary components, so a recompile should be much faster than doing a
second compile. This requires -sourceroots.
-sourceroots DirPaths
Find and build all .java or .aj source files under any directory listed in DirPaths. DirPaths,
like classpath, is a single argument containing a list of paths to directories, delimited by
the platform- specific classpath delimiter. Required by -incremental.
-crossrefs
Generate a build .ajsym file into the output directory. Used for viewing crosscutting
references by tools like the AspectJ Browser.
-emacssym Generate .ajesym symbol files for emacs support (deprecated).
-Xlint Same as -Xlint:warning (enabled by default)
-Xlint:{level}
Set default level for messages about potential programming mistakes in crosscutting code.
{level} may be ignore, warning, or error. This overrides entries in
org/aspectj/weaver/XlintDefault.properties from aspectjtools.jar, but does not override levels
set using the -Xlintfile option.
-Xlintfile PropertyFile
Specify properties file to set levels for specific crosscutting messages. PropertyFile is a
path to a Java .properties file that takes the same property names and values as
org/aspectj/weaver/XlintDefault.properties from aspectjtools.jar, which it also overrides.
-help Emit information on compiler options and usage
-version Emit the version of the AspectJ compiler
-classpath Path
Specify where to find user class files. Path is a single argument containing a list of paths
to zip files or directories, delimited by the platform-specific path delimiter.
-bootclasspath Path
Override location of VM's bootclasspath for purposes of evaluating types when compiling. Path
is a single argument containing a list of paths to zip files or directories, delimited by the
platform-specific path delimiter.
-extdirs Path
Override location of VM's extension directories for purposes of evaluating types when
compiling. Path is a single argument containing a list of paths to directories, delimited by
the platform-specific path delimiter.
-d Directory
Specify where to place generated .class files. If not specified, Directory defaults to the
current working dir.
-target [1.1 to 1.5]
Specify classfile target setting (1.1 to 1.5, default is 1.2)
-1.3 Set compliance level to 1.3 This implies -source 1.3 and -target 1.1.
-1.4 Set compliance level to 1.4 (default) This implies -source 1.4 and -target 1.2.
-1.5 Set compliance level to 1.5. This implies -source 1.5 and -target 1.5.
-source [1.3|1.4|1.5]
Toggle assertions (1.3, 1.4, or 1.5 - default is 1.4). When using -source 1.3, an assert()
statement valid under Java 1.4 will result in a compiler error. When using -source 1.4, treat
assert as a keyword and implement assertions according to the 1.4 language spec. When using
-source 1.5, Java 5 language features are permitted.
-nowarn Emit no warnings (equivalent to '-warn:none') This does not suppress messages generated by
declare warning or Xlint.
-warn: items
Emit warnings for any instances of the comma-delimited list of questionable code (eg
'-warn:unusedLocals,deprecation'):
constructorName method with constructor name
packageDefaultMethod attempt to override package-default method
deprecation usage of deprecated type or member
maskedCatchBlocks hidden catch block
unusedLocals local variable never read
unusedArguments method argument never read
unusedImports import statement not used by code in file
none suppress all compiler warnings
-warn:none does not suppress messages generated by declare warning or Xlint.
-deprecation
Same as -warn:deprecation
-noImportError
Emit no errors for unresolved imports
-proceedOnError
Keep compiling after error, dumping class files with problem methods
-g:[lines,vars,source]
debug attributes level, that may take three forms:
-g all debug info ('-g:lines,vars,source')
-g:none no debug info
-g:{items} debug info for any/all of [lines, vars, source], e.g.,
-g:lines,source
-preserveAllLocals
Preserve all local variables during code generation (to facilitate debugging).
-referenceInfo
Compute reference information.
-encoding format
Specify default source encoding format. Specify custom encoding on a per file basis by
suffixing each input source file/folder name with '[encoding]'.
-verbose Emit messages about accessed/processed compilation units
-showWeaveInfo
Emit messages about weaving
-log file Specify a log file for compiler messages.
-progress Show progress (requires -log mode).
-time Display speed information.
-noExit Do not call System.exit(n) at end of compilation (n=0 if no error)
-repeat N Repeat compilation process N times (typically to do performance analysis).
-XterminateAfterCompilation
Causes compiler to terminate before weaving
-XaddSerialVersionUID
Causes the compiler to calculate and add the SerialVersionUID field to any type implementing
Serializable that is affected by an aspect. The field is calculated based on the class before
weaving has taken place.
-Xreweavable[:compress]
(Experimental - deprecated as now default) Runs weaver in reweavable mode which causes it to
create woven classes that can be rewoven, subject to the restriction that on attempting a
reweave all the types that advised the woven type must be accessible.
-XnoInline
(Experimental) do not inline around advice
-XincrementalFile file
(Experimental) This works like incremental mode, but using a file rather than standard input to
control the compiler. It will recompile each time file is changed and and halt when file is
deleted.
-XserializableAspects
(Experimental) Normally it is an error to declare aspects Serializable. This option removes
that restriction.
-XnotReweavable
(Experimental) Create class files that can't be subsequently rewoven by AspectJ.
-Xajruntimelevel:1.2, ajruntimelevel:1.5
(Experimental) Allows code to be generated that targets a 1.2 or a 1.5 level AspectJ runtime
(default 1.5)
File names
ajc accepts source files with either the .java extension or the .aj extension. We normally use .java
for all of our files in an AspectJ system -- files that contain aspects as well as files that contain
classes. However, if you have a need to mechanically distinguish files that use AspectJ's additional
functionality from those that are pure Java we recommend using the .aj extension for those files.
We'd like to discourage other means of mechanical distinction such as naming conventions or sub-packages
in favor of the .aj extension.
• Filename conventions are hard to enforce and lead to awkward names for your aspects. Instead of
TracingAspect.java we recommend using Tracing.aj (or just Tracing.java) instead.
• Sub-packages move aspects out of their natural place in a system and can create an artificial need
for privileged aspects. Instead of adding a sub-package like aspects we recommend using the .aj
extension and including these files in your existing packages instead.
Compatibility
AspectJ is a compatible extension to the Java programming language. The AspectJ compiler adheres to the
The Java Language Specification, Second Edition (BOOK) http://java.sun.com/docs/books/jls/index.html and
to the The Java Virtual Machine Specification, Second Edition (BOOK)
http://java.sun.com/docs/books/vmspec/index.html and runs on any Java 2 compatible platform. The code it
generates runs on any Java 1.1 or later compatible platform. For more information on compatibility with
Java and with previous releases of AspectJ, see "" >.
Examples
A simple example
Compile two files:
ajc HelloWorld.java Trace.java
An example using -argfile/@
To avoid specifying file names on the command line, list source files in a line-delimited text argfile.
Source file paths may be absolute or relative to the argfile, and may include other argfiles by
@-reference. The following file sources.lst contains absolute and relative files and
@-references:
Gui.java
/home/user/src/Library.java
data/Repository.java
data/Access.java
@../../common/common.lst
@/home/user/src/lib.lst
view/body/ArrayView.java
Compile the files using either the -argfile or @ form:
ajc -argfile sources.lst
ajc @sources.lst
Argfiles are also supported by jikes and javac, so you can use the files in hybrid builds. However, the
support varies:
• Only ajc accepts command-line options
• Jikes and Javac do not accept internal @argfile references.
• Jikes and Javac only accept the @file form on the command line.
An example using -inpath and -aspectpath
Bytecode weaving using -inpath: AspectJ 1.2 supports weaving .class files in input zip/jar files and
directories. Using input jars is like compiling the corresponding source files, and all binaries are
emitted to output. Although Java-compliant compilers may differ in their output, ajc should take as
input any class files produced by javac, jikes, eclipse, and, of course, ajc. Aspects included in
-inpath will be woven into like other .class files, and they will affect other types as usual.
Aspect libraries using -aspectpath: AspectJ 1.1 supports weaving from read-only libraries containing
aspects. Like input jars, they affect all input; unlike input jars, they themselves are not affected or
emitted as output. Sources compiled with aspect libraries must be run with the same aspect libraries on
their classpath.
The following example builds the tracing example in a command-line environment; it creates a read-only
aspect library, compiles some classes for use as input bytecode, and compiles the classes and other
sources with the aspect library.
The tracing example is in the AspectJ distribution ({aspectj}/doc/examples/tracing). This uses the
following files:
aspectj1.1/
bin/
ajc
lib/
aspectjrt.jar
examples/
tracing/
Circle.java
ExampleMain.java
lib/
AbstractTrace.java
TraceMyClasses.java
notrace.lst
Square.java
tracelib.lst
tracev3.lst
TwoDShape.java
version3/
Trace.java
TraceMyClasses.java
Below, the path separator is taken as ";", but file separators are "/". All commands are on one line.
Adjust paths and commands to your environment as needed.
Setup the path, classpath, and current directory:
cd examples
export ajrt=../lib/aspectjrt.jar
export CLASSPATH="$ajrt"
export PATH="../bin:$PATH"
Build a read-only tracing library:
ajc -argfile tracing/tracelib.lst -outjar tracelib.jar
Build the application with tracing in one step:
ajc -aspectpath tracelib.jar -argfile tracing/notrace.lst -outjar tracedapp.jar
Run the application with tracing:
java -classpath "$ajrt;tracedapp.jar;tracelib.jar" tracing.ExampleMain
Build the application with tracing from binaries in two steps:
• (a) Build the application classes (using javac for demonstration's sake):
mkdir classes
javac -d classes tracing/*.java
jar cfM app.jar -C classes .
• (b) Build the application with tracing:
ajc -inpath app.jar -aspectpath tracelib.jar -outjar tracedapp.jar
Run the application with tracing (same as above):
java -classpath "$ajrt;tracedapp.jar;tracelib.jar" tracing.ExampleMain
Run the application without tracing:
java -classpath "app.jar" tracing.ExampleMain
The AspectJ compiler API
The AspectJ compiler is implemented completely in Java and can be called as a Java class. The only
interface that should be considered public are the public methods in org.aspectj.tools.ajc.Main. E.g.,
main(String[] args) takes the the standard ajc command line arguments. This means that an alternative
way to run the compiler is
java org.aspectj.tools.ajc.Main [option...] [file...]
To access compiler messages programmatically, use the methods setHolder(IMessageHolder holder) and/or
run(String[] args, IMessageHolder holder). ajc reports each message to the holder using
IMessageHolder.handleMessage(..). If you just want to collect the messages, use MessageHandler as
your IMessageHolder. For example, compile and run the following with aspectjtools.jar on the
classpath:
import org.aspectj.bridge.*;
import org.aspectj.tools.ajc.Main;
import java.util.Arrays;
public class WrapAjc {
public static void main(String[] args) {
Main compiler = new Main();
MessageHandler m = new MessageHandler();
compiler.run(args, m);
IMessage[] ms = m.getMessages(null, true);
System.out.println("messages: " + Arrays.asList(ms));
}
}
Stack Traces and the SourceFile attribute
Unlike traditional java compilers, the AspectJ compiler may in certain cases generate classfiles from
multiple source files. Unfortunately, the original Java class file format does not support multiple
SourceFile attributes. In order to make sure all source file information is available, the AspectJ
compiler may in some cases encode multiple filenames in the SourceFile attribute. When the Java VM
generates stack traces, it uses this attribute to specify the source file.
(The AspectJ 1.0 compiler also supports the .class file extensions of JSR-45. These permit compliant
debuggers (such as jdb in Java 1.4.1) to identify the right file and line even given many source files
for a single class. JSR-45 support is planned for ajc in AspectJ 1.1, but is not in the initial release.
To get fully debuggable .class files, use the -XnoInline option.)
Probably the only time you may see this format is when you view stack traces, where you may encounter
traces of the format
java.lang.NullPointerException
at Main.new$constructor_call37(Main.java;SynchAspect.java[1k]:1030)
where instead of the usual
File:LineNumber
format, you see
File0;File1[Number1];File2[Number2] ... :LineNumber
In this case, LineNumber is the usual offset in lines plus the "start line" of the actual source file.
That means you use LineNumber both to identify the source file and to find the line at issue. The number
in [brackets] after each file tells you the virtual "start line" for that file (the first file has a
start of 0).
In our example from the null pointer exception trace, the virtual start line is 1030. Since the file
SynchAspect.java "starts" at line 1000 [1k], the LineNumber points to line 30 of SynchAspect.java.
So, when faced with such stack traces, the way to find the actual source location is to look through the
list of "start line" numbers to find the one just under the shown line number. That is the file where
the source location can actually be found. Then, subtract that "start line" from the shown line number
to find the actual line number within that file.
In a class file that comes from only a single source file, the AspectJ compiler generates SourceFile
attributes consistent with traditional Java compilers.
ajc(1)