Provided by: ecj_3.35.0+eclipse4.29-2_all 
NAME
ecj - the eclipse JDT Batch Compiler
SYNOPSIS
ecj [OPTION]... [SOURCEFILE]... ...
DESCRIPTION
ecj is the batch compiler from Eclipse and is available as ecj.jar. Since 3.3, this jar
also contains the support for jsr199 (Compiler API) and the support for jsr269 (Annotation
processing). In order to use the annotations processing support, a 1.6 VM is required.
OPTIONS SUMMARY
Here is a summary of all the options, grouped by type. Explanations are in the OPTIONS
section.
Module Options
--add-exports --add-modules --add-reads --limit-modules -p|--module-path --module-source-
path --processor-module-path --system
ClassPath Options
-bootclasspath -cp|-classpath -extdirs -endorseddirs -sourcepath -d -encoding
Compliance Options
-target -1.3 -1.4 -1.5 -1.6 -1.7 -1.8 1.9 -source --release
Warning Options
-?:warn -help:warn -warn:... -nowarn -err:... -deprecation -properties
Debug Options
-g -preserveAllLocals -parameters
Annotation Processing Options
-Akey[=value] -proc:[only|none] -processor -processorpath -s -XprintProcessorInfo
-XprintRounds -classNames
Ignored Options (for compatibility with javac options)
-J -X -O
Advanced Options
@<file> -maxProblems -log -Xemacs -proceedOnError -verbose -referenceInfo -progress -time
-noExit -repeat -inlineJSR -enableJavaDoc -missingNullDefault
Helping Options
-? -help -v -version -showversion
OPTIONS
Module Options (Supported from 9 onwards)
--add-exports <source-module>/<package>=<target-module>(,<target-module>)*
A command line form of exports statement which exports the package in source-module
to the comma separated list of target modules.
--add-modules <module 1>,<module 2>,...,<module P>
Extend the default set of root modules with a list of comma separated modules.
--add-reads <source-module>=<target-module>
A command line form of a requires clause equivalent to adding requires source-
module in target modules module-info file.
--limit-modules <module 1>,<module 2>,...,<module P>
Limit the observable modules to the list of comma separated modules.
-p|--module-path <dir 1>;<dir 2>;...;<dir P>
This is a list of directories where application modules can be found. Entries are
separated by the platform path separator.
--module-source-path <dir 1>;<dir 2>;...;<dir P>
This is a list of directories where source files for modules can be found. Entries
are separated by the platform path separator.
--processor-module-path <path>
module path where annotation processors can be found.
--system <jdk>
Override location of system modules.
ClassPath Options
-bootclasspath <dir 1>;<dir 2>;...;<dir P>
This is a list of directories or jar files used to bootstrap the class files used
by the compiler. By default the libraries of the running VM are used. Entries are
separated by the platform path separator. Each directory or file can specify
access rules for types between '[' and ']'. If no bootclasspath is specified, the
compiler will infer it using the following system properties sun.boot.class.path,
vm.boot.class.path or org.apache.harmony.boot.class.path in this order respectively
-cp|-classpath <dir 1>;dir2;...<dir P>
This is a list of directories or jar files used to compile the source files. The
default value is the value of the property "java.class.path". Entries are separated
by the platform path separator. Each directory or file can specify access rules
for types between '[' and ']' (e.g. [-X] to forbid access to type X, [~X] to
discourage access to type X, [+p/X:-p/*] to forbid access to all types in package p
but allow access to p/X). The compiler follows the Class-Path clauses of jar
files' manifests recursively and appends each referenced jar file to the end of the
classpath, provided it is not on the classpath yet.
-extdirs <dir 1>;<dir 2>;...;<dir P>
This is a list of directories used to specify the location of extension zip/jar
files. Entries are separated by the platform path separator.
-endorseddirs <dir 1>;<dir 2>;...;<dir P>
This is a list of directories used to specify the location of endorsed zip/jar
files. Entries are separated by the platform path separator.
-sourcepath <dir 1>;<dir 2>;...;<dir P>
This is a list of directories used to specify the source files. Entries are
separated by the platform path separator. Each directory can specify access rules
for types between '[' and ']'.
-d <dir 1>|none
This is used to specify in which directory the generated .class files should be
dumped. If it is omitted, no package directory structure is created. If you want
to generate no .class file at all, use -d none.
-encoding <encoding name>
Specify default encoding for all source files. Custom encoding can also be
specified on a per file basis by suffixing each input source file/folder name with
[<encoding name>]. For example X.java[UTF-8] would specify the UTF-8 encoding for
the compilation unit X.java located in the current user directory. If multiple
default source file encodings are specified, the last one will be used.
For example: ... -encoding UTF-8 X.java[Cp1252] Y.java[UTF-16] Z.java ....
All source files will be read using UTF-8 encoding (this includes Z.java). X.java
will be read using Cp1252 encoding and Y.java will be read using UTF-16 encoding.
... -encoding UTF-8 -encoding UTF-16 ....
All source files will be read using UTF-16 encoding. The -encoding option for UTF-8
is ignored.
... -encoding Cp1252 /foo/bar/X.java[UTF-16] /foo/bar[UTF-8] ....
All source files will be read using Cp1252 encoding. X.java is the only file inside
the /foo/bar directory to be read using the encoding UTF-16. All other files in
that directory will use UTF-8 encoding.
Compliance Options
-target 1.1 to 1.9 (or 9, 9.0, etc.)
This specifies the .class file target setting. The possible value are:
1.1 (major version: 45 minor: 3)
1.2 (major version: 46 minor: 0)
1.3 (major version: 47 minor: 0)
1.4 (major version: 48 minor: 0)
1.5, 5 or 5.0 (major version: 49 minor: 0)
1.6, 6 or 6.0 (major version: 50 minor: 0)
1.7, 7 or 7.0 (major version: 51 minor: 0)
1.8, 8 or 8.0 (major version: 52 minor: 0)
1.9, 9 or 9.0 (major version: 53 minor: 0)
Defaults are:
1.1 in -1.3 mode
1.2 in -1.4 mode
1.5 in -1.5 mode
1.6 in -1.6 mode
1.7 in -1.7 mode
1.8 in -1.8 mode
1.9 in -1.9 mode clcd1.1 can be used to generate the StackMap attribute.
-1.3 Set compliance level to 1.3. Implicit -source 1.3 -target 1.1.
-1.4 Set compliance level to 1.4 (default). Implicit -source 1.3 -target 1.2.
-1.5 Set compliance level to 1.5. Implicit -source 1.5 -target 1.5.
-1.6 Set compliance level to 1.6. Implicit -source 1.6 -target 1.6.
-1.7 Set compliance level to 1.7. Implicit -source 1.7 -target 1.7.
-1.8 Set compliance level to 1.8. Implicit -source 1.8 -target 1.8.
-1.9 Set compliance level to 1.9. Implicit -source 1.9-target 1.9.
-source 1.1 to 1.9 (or 9, 9.0, etc.)
This is used to specify the source level expected by the compiler. The possible
value are:
1.3
1.4
1.5, 5 or 5.0
1.6, 6 or 6.0
1.7, 7 or 7.0
1.8, 8 or 8.0
1.9, 9 or 9.0
Defaults are:
1.3 in -1.3 mode
1.3 in -1.4 mode
1.5 in -1.5 mode
1.6 in -1.6 mode
1.7 in -1.7 mode
1.8 in -1.8 mode
1.9 in -1.9 mode
In 1.4, assert is treated as a keyword. In 1.5 and 1.6, enum and assert are treated
as keywords.
--release N
Compile for a specific VM version. Used for compiling against older APIs.
Warning Options
-?:warn -help:warn
Display advanced warning options
-warn:...
Specify the set of enabled warnings.
-warn:none disable all warnings
-warn:<warning tokens separated by ,> enable exactly the listed warnings
-warn:+<warning tokens separated by ,> enable additional warnings
-warn:-<warning tokens separated by ,> disable specific warnings
Examples:
warn:unusedLocal,deprecation
enables only the given two warning options and disables all the other options
warn:-unusedLocal,deprecation,+fallthrough
disables unusedLocal and deprecation, enables fallthrough, and leaves the other
warning options untouched
The first column below shows the default state for an option. A mark "+/-"
indicates that an option covers several fine grained warning variants, some of
which are enabled by default, others disabled. This means that specifying the given
option with "+" will enable more warnings than the default, and specifying "-"
disables some that are enabled by default.
+/- allDeadCode dead code including trivial if (DEBUG) check
+/- allDeprecation deprecation even inside deprecated code
- allJavadoc invalid or missing Javadoc
- allOver-ann all missing @Override annotations (superclass and superinterfaces)
- all-static-method all method can be declared as static warnings
+ assertIdentifier occurrence of assert used as identifier
- boxing autoboxing conversion
+ charConcat when a char array is used in a string concatenation without being
converted explicitly to a string
+ compareIdentical comparing identical expressions
- conditionAssign possible accidental boolean assignment
+ constructorName method with constructor name
+ deadCode dead code excluding trivial if (DEBUG) check
- dep-ann missing @Deprecated annotation
+/- deprecation usage of deprecated type or member outside deprecated code
+ discouraged use of types matching a discouraged access rule
- emptyBlock undocumented empty block
+ enumIdentifier occurrence of enum used as identifier
+ enumSwitch incomplete enum switch
- enumSwitchPedantic report missing enum switch cases even in the presence of a
default case
- fallthrough possible fall-through case
- fieldHiding field hiding another variable
+ finalBound type parameter with final bound
+ finally finally block not completing normally
+ forbidden use of types matching a forbidden access rule
- hashCode missing hashCode() method when overriding equals()
+/- hiding macro for fieldHiding, localHiding, maskedCatchBlock, and typeHiding
- includeAssertNull raise null warnings for variables that got tainted in an
assert expression
- indirectStatic indirect reference to static member
- inheritNullAnnot consider null annotations as being inherited from an
overridden method to any overriding methods
+ intfAnnotation annotation type used as super interface
+ intfNonInherited interface non-inherited method compatibility
- intfRedundant find redundant superinterfaces
- invalidJavadoc macro to toggle the 'malformed Javadoc comments' option and all
its sub-options listed below
- invalidJavadocTag report invalid Javadoc tags in Javadoc comments.
- invalidJavadocTagDep report invalid deprecated references in Javadoc tag
arguments
- invalidJavadocTagNotVisible report invalid non-visible references in Javadoc
tag arguments
- invalidJavadocVisibility(<visibility>) specify visibility modifier ("public",
"protected" or "private") for malformed Javadoc tag warnings. Usage example:
invalidJavadocVisibility(public)
- javadoc invalid Javadoc
- localHiding local variable hiding another variable
+ maskedCatchBlock hidden catch block
- missingJavadocTags macro to toggle the 'missing Javadoc tags' option and all
its sub-options listed below
- missingJavadocTagsMethod report missing Javadoc tags for a method's type
parameters
- missingJavadocTagsOverriding report missing Javadoc tags in overriding methods
- missingJavadocTagsVisibility(<visibility>) specify visibility modifier
("public", "protected" or "private") for missing Javadoc tags warnings. Usage
example: missingJavadocTagsVisibility(public)
- missingJavadocComments macro to toggle the 'missing Javadoc comments' option
and all its sub-options listed below
- missingJavadocCommentsOverriding report missing Javadoc comments in overriding
methods
- missingJavadocCommentsVisibility(<visibility>) specify visibility modifier
("public", "protected" or "private") for missing Javadoc comments warnings. Usage
example: missingJavadocCommentsVisibility(public)
- nls non-nls string literals (lacking of tags //$NON-NLS-<n>)
+ noEffectAssign assignment with no effect
+ nonnullNotRepeated nonnull parameter annotation from overridden method is not
repeated in an overriding method. Is effective only with the nullAnnot option
enabled.
+/- null potential missing or redundant null check
- nullAnnot enable annotation based null analysis. If desired, the annotation
types to be interpreted by the compiler can be specified by appending
(nullable|nonnull|nonnullbydefault), where each annotation type is specified using
its fully qualified name. Usage example:
nullAnnot(p.Nullable|p.NonNull|p.NonNullByDefault)
Enabling this option enables all null-annotation related sub-options. These can be
individually controlled using options listed below
- nullAnnotConflict report conflicts between null annotation specified and
nullness inferred. Is effective only with the nullAnnot option enabled.
- nullAnnotRedundant report redundant specification of null annotation. Is
effective only with the nullAnnot option enabled.
- nullDereference missing null check
- nullUncheckedConversion report unchecked conversion from unannotated type to
@NonNull type. Is effective only with the nullAnnot option enabled.
- over-ann missing @Override annotation (superclass only)
- paramAssign assignment to a parameter
+ pkgDefaultMethod attempt to override package-default method
+ raw usage a of raw type (instead of a parameterized type)
+/- resource (potentially) unsafe usage of resource of type Closeable
- semicolon unnecessary semicolon or empty statement
+ serial missing serialVersionUID
- specialParamHiding constructor or setter parameter hiding another field
+/- static-access macro for indirectStatic and staticReceiver
- static-method an instance method that could be as a static method
+ staticReceiver if a non static receiver is used to get a static field or call a
static method
- super overriding a method without making a super invocation
+ suppress enable @SuppressWarnings
- switchDefault switch statement lacking a default case
- syncOverride missing synchronized in synchronized method override
- syntacticAnalysis perform syntax-based null analysis for fields
- syntheticAccess when performing synthetic access for innerclass
- tasks enable support for tasks tags in source code
+ typeHiding type parameter hiding another type
+ unavoidableGenericProblems report even unavoidable type safety problems due to
raw APIs
+ unchecked unchecked type operation
- unnecessaryElse unnecessary else clause
- unqualifiedField unqualified reference to field
+/- unused macro for unusedImport, unusedLabel, unusedLocal, unusedPrivate,
unusedThrown, unusedTypeArgs, and unusedTypeParameter
- unusedAllocation allocating an object that is not used
- unusedArgument unused method parameter (deprecated option; use unusedParam
instead)
+ unusedImport unused import reference
+ unusedLabel unused label
+ unusedLocal unused local variable
+ unusedParam unused method parameter
+ unusedParamImplementing unused parameter for implementing method
+ unusedParamIncludeDoc unused parameter documented in a Javadoc comment tag
+ unusedParamOverriding unused parameter for overriding method
+ unusedPrivate unused private member declaration
- unusedThrown unused declared thrown exception
- unusedThrownIncludeDocComment unused declared thrown exception documented in a
Javadoc comment tag
- unusedThrownExemptExceptionThrowable report unused declared thrown exception
but exempt Exception and Throwable
- unusedThrownWhenOverriding unused declared thrown exception in overriding
method
+ unusedTypeArgs unused type arguments for method and constructor
+ unusedTypeParameter unused type parameter
- uselessTypeCheck unnecessary cast/instanceof operation
+ varargsCast varargs argument need explicit cast
+/- warningToken unhandled or unused warning token in @SuppressWarnings
-nowarn
No warning (equivalent to -warn:none)
-err:...
Specify the set of enabled warnings that are converted to errors.
E.g.
-err:unusedLocal,deprecation
unusedLocal and deprecation warnings will be converted to errors. All other
warnings are still reported as warnings.
-err:<warning tokens separated by ,> convert exactly the listed warnings to
errors
-err:+<warning tokens separated by ,> convert additional warnings to errors
-err:-<warning tokens separated by ,> remove specific warnings from being
converted to errors
-deprecation
Equivalent to -warn:+deprecation.
-properties <file>
Set warnings/errors option based on the properties file contents. This option can
be used with -nowarn, -err:.. or -warn:.. options, but the last one on the command
line sets the options to be used.
The properties file contents can be generated by setting project specific settings
on an existing java project and using the file in
.settings/org.eclipse.jdt.core.prefs file as a properties file, or a simple text
file that is defined entry/value pairs using the constants defined in the
org.eclipse.jdt.core.JavaCore class. Of those constants declared in this class, all
options starting with "org.eclipse.jdt.core.compiler." are interpreted by the batch
compiler.
...
org.eclipse.jdt.core.compiler.problem.annotationSuperInterface=warning
org.eclipse.jdt.core.compiler.problem.assertIdentifier=warning
org.eclipse.jdt.core.compiler.problem.autoboxing=ignore
...
To ensure that a property file has the same effect when used in the IDE and for the
batch compiler, use of the -properties option will change the defaults for a few
options:
-g default changed to all enabled
-preserveAllLocals default changed to enabled
-enableJavadoc default changed to enabled
error/warning forbidden default changed to error
Debug Options
-g[:none|:lines,vars,source]
Set the debug attributes level
-g All debug info (equivalent to -g:lines,vars,source)
-g:none No debug info
-g:[lines,vars,source] Selective debug info
Not specifying this option is equivalent to setting -g:lines,source.
-preserveAllLocals
Explicitly request the compiler to preserve all local variables (for debug
purpose). If omitted, the compiler will remove unused locals.
-parameters
Explicitly request the compiler to preserve information about the formal parameters
of a method (such as their names) to be accessed from reflection libraries,
annotation processing, code weaving, and in the debugger. This option is supported
from target level 1.8 and later. Annotation processing options (require a 1.6 VM
or above and are used only if the compliance is 1.6)
Annotation Processing Options
-Akey[=value]
Annotation processors options that are passed to annotation processors. key is made
of identifiers separated by dots
-proc:[only|none]
If -proc:only is specified, the annotation processors will run but no compilation
will be performed. If -proc:none is specified, annotation processors will not be
discovered or run; compilation will proceed as if no annotation processors were
found. By default the compiler must search the classpath for annotation processors,
so specifying -proc:none may speed compilation if annotation processing is not
required.
-processor <class1[,class2,...]>
Qualified class names of annotation processors to run. If specified, the normal
processor discovery process will be skipped.
-processorpath <dir 1>;<dir 2>;...;<dir P>
A list of directories or jar files which will be searched for annotation
processors. Entries are separated by the platform path separator. If not specified,
the classpath will be searched instead.
-s <dir>
The directory where generated source files will be created.
-XprintProcessorInfo
Print information about which annotations and which elements a processor is asked
to process
-XprintRounds
Print information about annotation processing rounds
-classNames <class1[,class2,...]>
Qualified names of binary types that need to be processed
Ignored Options (for compatibility with javac options)
-J<option>
Pass option to the virtual machine
-X<option>
Specify non-standard option. -Xemacs is not ignored.
-X Print non-standard options and exit
-O Optimize for execution time
Advanced Options
@<file>
Read command-line arguments from file
-maxProblems <n>
Max number of problems per compilation unit (100 by default)
-log <filename>
Specify a log file in which all output from the compiler will be dumped. This is
really useful if you want to debug the batch compiler or get a file which contains
all errors and warnings from a batch build. If the extension is .xml, the generated
log will be an xml file.
-genericsignature
Explicitly request the compiler to preserve information about generic signature of
lambda expressions.
-Xemacs
Use emacs style to present errors and warnings locations into the console and
regular text logs. XML logs are unaffected by this option. With this option active,
the message:
2. WARNING in /workspace/X.java
(at line 8)...
is presented as:
/workspace/X.java:8: warning: The method...
-proceedOnError[:Fatal]
Keep compiling in spite of errors, dumping class files with problem methods or
problem types. This is recommended only if you want to be able to run your
application even if you have remaining errors. With ":Fatal", all optional errors
are treated as fatal and this leads to code that will abort if an error is reached
at runtime. Without ":Fatal", optional errors don't prevent the proper code
generation and the produced .class files can be run without a problem.
-verbose
Print accessed/processed compilation units in the console or the log file if
specified.
-referenceInfo
Compute reference info. This is useful only if connected to the builder. The
reference infos are useless otherwise.
-progress
Show progress (only in -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 (perf analysis).
-inlineJSR
Inline JSR bytecode (implicit if target >= 1.5).
-enableJavadoc
Consider references inside Javadoc. The Javadoc options are effective only when
this option is enabled.
-missingNullDefault
When annotation based null analysis is enabled (using "nullAnnot", above), this
option will raise a warning whenever there is no default annotation on a package or
a type.
-annotationpath
When annotation based null analysis is enabled (using "nullAnnot", above), this
option defines locations where to find external annotations to support annotation-
based null analysis. The value of this options is a list of directories or zip
files. Entries are separated by the platform path separator. The special name
CLASSPATH will cause lookup of external annotations from the classpath and
sourcepath.
Helping Options
-? -help
Display the help message.
-v -version
Display the build number of the compiler. This is very useful to report a bug.
-showversion
Display the build number of the compiler and continue. This is very useful to
report a bug.
SEE ALSO
<http://help.eclipse.org/topic/org.eclipse.jdt.doc.user/tasks/task-
using_batch_compiler.htm>
BUGS
To report bugs, use
<https://bugs.eclipse.org/bugs/enter_bug.cgi?product=JDT&component=Core>
AUTHOR
For details on Eclipse committers, see <http://www.eclipse.org/committers/>
13 March 2017 ecj(1)