mileshoogl.blogg.se - Java reflection tutorial

#JAVA REFLECTION TUTORIAL HOW TO#
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#JAVA REFLECTION TUTORIAL SOFTWARE#
#JAVA REFLECTION TUTORIAL CODE#

Methods.addAll(Arrays.asList(clazz.getDeclaredMethods())) Public static Method getAllMethods(final Class clazz) Return findMethod(clazz.getSuperclass(), methodName, parameterTypes) Return clazz.getDeclaredMethod(methodName, parameterTypes) Public static Method findMethod(final Class clazz, final String methodName, final Class. Return findField(clazz.getSuperclass(), fieldName) Return clazz.getDeclaredField(fieldName)

Public static Field findField(final Class clazz, final String fieldName) Public static String modifierToString(final int modifier) * verschiedene Hilfsmethoden zur vereinfachten Handhabung von Reflection * Die Klasse ReflectionUtils ist eine Utility-Klasse, die Java source – The helper class: ReflectionUtils.java package utils Java source: CanConstruct.java package utils Java source: CanChange.java package utils

Java source: ClassInfo.java package utils Construct a new AnnotationRunner instance and printout the int field id1 by using reflection code:ĪnnotationRunner r = (AnnotationRunner)ctor.newInstance() įield f = r.getClass().getDeclaredField("id1") į.setAccessible(true) Note all of the above Anotations are used during Runtime and thus = RetentionPolicy.RUNTIME) is mandatory Indicates that we can/should run a certain JAVA Constructor via reflection Change a int field by using reflection code:į.setInt(runner,k) CanConstruct - = ElementType.CONSTRUCTOR) Indicate that we can/should modify a certain JAVA methode via reflection Method.invoke(runner) CanChange - = ElementType.FIELD) Run that specific methode by using reflection code: Indicate that we can/should run a certain JAVA methode via reflection

#JAVA REFLECTION TUTORIAL CODE#

Use reflection code below to display the Anotation InfoĬlassInfo myAnnotation = (ClassInfo) annotation Provide some Info who has changed a certain specific JAVA source

Annotation can also be used to provide some info about who change a component Ĭustom Annotations Details for Runtime processing with Reflection ClassInfo - = ElementType.TYPE).

#JAVA REFLECTION TUTORIAL HOW TO#

Later, the JVM or other programs can look for the metadata to determine how to interact with the program elements or change their behavior

The Java compiler conditionally stores annotation metadata in the class files if the annotation has a RetentionPolicy of CLASS or RUNTIME.

Following JAVA language constructs can be annotated: Class, Constructor, Field, Method, and Package.

Rather any tool like JPA need to extract the annotations at runtime and need to do execute the designed action like: Generating an object-relational mapping.

The annotations are not method calls and will not, by themselves, do anything.

An at-sign precedes the interface keyword – Sample : public ClassInfo.

Annotation type declarations are similar to normal interface declarations.

Runtime processing - Some annotations are available to be examined at runtime.

#JAVA REFLECTION TUTORIAL SOFTWARE#

Compile-time and deployment-time processing - Software tools can process annotation information to generate code, XML files, and so forth.

Information for the compiler - Annotations can be used by the compiler to detect errors or suppress warnings.

Annotations have a number of uses, among them:.

Java source – The helper class: ReflectionUtils.java.

Custom Annotations Details for Runtime processing with Reflection.

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#JAVA REFLECTION TUTORIAL PATCH#

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