annotation for class
Below programs demonstrate the getAnnotation() method. Example 1: filter_none edit play_arrow brightness_4 // Java program to demonstrate // getAnnotation() method import java.util.*; import java.lang.annotation.*; // create a custom Annotation @Retention(RetentionPolicy.RUNTIME) @interface Annotation { // This annotation has two attributes. public String key(); public String value(); } // call Annotation for method // and pass values for annotation @Annotation(key = "GFG", value = "GeeksForGeeks") public class Test { public static void main(String[] args) throws ClassNotFoundException { // returns the Class object for this class Class myClass = Test.class; System.out.println("Class represented by myClass: " + myClass.toString()); // Get the annotation // using getAnnotation() method System.out.println( "Annotation of myClass: " + myClass.getAnnotation( Annotation.class)); } }
annotation for method
package com.yiibai; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.reflect.Method; // declare a new annotation @Retention(RetentionPolicy.RUNTIME) @interface Demo { String str(); int val(); } public class PackageDemo { // set values for the annotation @Demo(str = "Demo Annotation", val = 100) // a method to call in the main public static void example() { PackageDemo ob = new PackageDemo(); try { Class c = ob.getClass(); // get the method example Method m = c.getMethod("example"); // get the annotation for class Demo Demo annotation = m.getAnnotation(Demo.class); // print the annotation System.out.println(annotation.str() + " " + annotation.val()); } catch (NoSuchMethodException exc) { exc.printStackTrace(); } } public static void main(String args[]) { example(); } }
annotation for method
import java.lang.annotation.Annotation; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.reflect.Method; public class MethodDemo { public static void main(String[] args) { Method[] methods = SampleClass.class.getMethods(); Annotation[] annotations = methods[0].getDeclaredAnnotations(); for(Annotation annotation : annotations){ if(annotation instanceof CustomAnnotation){ CustomAnnotation customAnnotation = (CustomAnnotation) annotation; System.out.println("name: " + customAnnotation.name()); System.out.println("value: " + customAnnotation.value()); } } } } @CustomAnnotation(name="SampleClass", value = "Sample Class Annotation") class SampleClass { private String sampleField; @CustomAnnotation(name="getSampleMethod", value = "Sample Method Annotation") public String getSampleField() { return sampleField; } public void setSampleField(String sampleField) { this.sampleField = sampleField; } } @Retention(RetentionPolicy.RUNTIME) @interface CustomAnnotation { public String name(); public String value(); }
Method[] declaredMethods = this.getClass().getMethods(); for(int i = 0; i < declaredMethods.length; ++i) { Annotation[] methodAnnotations = declaredMethods[i].getDeclaredAnnotations(); for(int j = 0; j < methodAnnotations.length; ++j) { if (methodAnnotations[j] instanceof xx) { } } }