See also the code examples page.

• General usage pattern
• API index
• Documentation for legacy API (FastClasspathScanner)

1. Create a new ClassGraph() instance, and configure it for scanning:
   • Optionally call .verbose() to enable verbose logging to stderr.
   • Enable classfile scanning, if you want to scan classes -- in the simplest case, call .enableAllInfo() to enable the scanning of classes, methods, fields, and annotations.
   • Call .acceptPackages(String... packages) to accept specific packages to scan, or .acceptPaths(String... paths) if you only want to scan resources and not classes. If you don't call either of these methods, then all packages or paths will be scanned.
2. Start the scan, by calling .scan(), to produce a ScanResult object.

   💡 The ScanResult should be assigned in a try-with-resources block or equivalent. See ScanResult lifecycle.

3. Query the ScanResult object: (the ScanResult object can be queried repeatedly without re-running the scan)
   • For class scan results: Call methods such as .getAllClasses(), .getAllInterfaces() etc. to get ClassInfoList lists of ClassInfo objects for classes of interest
     • Query the ClassInfo objects for class properties or class relationships of interest.
       • Call ClassInfo#getMethodInfo() to get info on the methods of the class as a MethodInfoList of MethodInfo objects.
         • Call MethodInfo#getMethodParameterInfo() to get info on the parameters of a method as an array of MethodParameterInfo objects, one per parameter.
         • Call MethodInfo#getAnnotationInfo() to get the annotations on a method as an AnnotationInfoList of AnnotationInfo objects.
       • Call ClassInfo#getFieldInfo() to get info on the fields of a class as a FieldInfoList of FieldInfo objects.
         • Call FieldInfo#getAnnotationInfo() to the annotations on a field as an AnnotationInfoList of AnnotationInfo objects.
       • Call ClassInfo#getAnnotationInfo() to get the annotations on a class as an AnnotationInfoList of AnnotationInfo objects.
     • ClassInfoList lists can be filtered using .filter(predicateFunction) or combined using .union(ClassInfoList... others), .intersect(ClassInfoList... others), or .exclude(ClassInfoList other), to return a new ClassInfoList representing the predicate-filtered subset, union, intersection or set difference respectively.
   • And/or for resource scan results: Call methods such as .getAllResources(), .getResourcesWithPath(path), .getResourcesWithExtension(ext) etc. to get ResourceList lists of Resource (file) objects matching a given path or filename pattern.
     • Call methods ResourceList#forEachByteArray(ByteArrayConsumer) and similar functions to open the content of each Resource object as a ByteBuffer or InputStream, or read the complete contents into a byte[] array, then pass the buffer, stream or array to a consumer method, closing the buffer or stream when the consumer exits.

You can scan either at runtime (the normal usecase), or at build time (for faster startup speed, or to support Android, since it does not use the standard Java bytecode format).

See the code examples page for specific examples of how to use the ClassGraph API.

• Configuring the ClassGraph instance
• Starting the scan
• Processing the result of the scan:
  • ScanResult
    • (The scan result class. Use the ScanResult object to obtain references to ClassInfo or Resource objects.)
  • ScanResult lifecycle
• Classes:
  • Classes
    • ClassInfo
      • (The class metadata class. Use ClassInfo objects to obtain references to AnnotationInfo, MethodInfo, MethodParameterInfo or FieldInfo objects.)
    • ClassInfoList
  • Methods
    • MethodInfo
      • (The method metadata class. Use MethodInfo objects to obtain references to MethodParameterInfo objects, and/or AnnotationInfo objects for method annotations.)
    • MethodParameterInfo
      • (The method parameter metadata class. Use MethodParameterInfo objects to obtain references to AnnotationInfo objects for method parameter annotations.)
    • MethodInfoList
  • Fields
    • FieldInfo
      • (The field metadata class. Use FieldInfo objects to obtain references to AnnotationInfo objects for field annotations.)
    • FieldInfoList
  • Annotations
    • AnnotationInfo
      • (The annotation metadata class. Use AnnotationInfo objects to obtain references to AnnotationParameterValue objects for parameter values for specific annotation instances.)
    • AnnotationParameterValue
    • AnnotationEnumValue
    • AnnotationClassRef
    • AnnotationInfoList
  • Type signatures
    • TypeSignature
    • ReferenceTypeSignature
    • ClassRefOrTypeVariableSignature
    • ClassTypeSignature
    • ClassRefTypeSignature
    • TypeArgument
    • TypeVariableSignature
    • TypeParameter
    • ArrayTypeSignature
    • BaseTypeSignature
    • MethodTypeSignature
  • Packages:
    • PackageInfo
    • PackageInfoList
  • Modules:
    • ModuleInfo
    • ModuleInfoList
• Resources:
  • Resource
    • (The main metadata class for resource files encountered in accepted packages or paths during a scan.)
  • ResourceList
• Obtaining module references
  • ModuleRef
  • ModuleReaderProxy

ClassGraph version 4 is a major upgrade over the previous version, FastClasspathScanner version 3, and there were a number of major API changes between FastClasspathScanner and ClassGraph. See here for information on porting FastClasspathScanner v3 code to the ClassGraph v4 API, and for info on how to obtain the older FastClasspathScanner version 3 documentation.