Created
August 7, 2025 20:24
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Annotations in Java also Reflection
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| import java.lang.annotation.Annotation; | |
| import java.lang.annotation.Documented; | |
| import java.lang.annotation.Retention; | |
| import java.lang.annotation.RetentionPolicy; | |
| import java.lang.reflect.Method; | |
| @SomeAnnots(author = "First Last", date = "3/3/2025", currRev = 2, lastMod = "", lastModBy = "", reviewers = {"one", "two" }) | |
| public class Annot { | |
| @SomeAnnots(author = "Meth LasMeth", date = "2/2/2025", reviewers = { "fir", "sec" }) | |
| public void SomeMeth() throws Exception { | |
| Method m[] = getClass().getMethods(); | |
| // System.out.printf("Val is %s\n", m[1].getName()); | |
| Method me = getClass().getMethod("SomeMeth"); | |
| SomeAnnots an = me.getAnnotation(SomeAnnots.class); | |
| System.out.printf("Val is %s\n", an); | |
| Class cla = getClass(); | |
| Annotation val = cla.getAnnotation(SomeAnnots.class); | |
| System.out.printf("Val is %s\n", val); | |
| SomeAnnots ann = Class.forName("SomeAnn").getAnnotation(SomeAnnots.class); | |
| System.out.printf("Val is %s\n", ann); | |
| } | |
| public static void main(String as[]){ | |
| Annot ann = new Annot(); | |
| try { | |
| ann.SomeMeth(); | |
| } | |
| catch (Exception ex){ | |
| System.out.printf("Exception is %s", ex.getMessage()); | |
| } | |
| } | |
| } | |
| @Documented | |
| @Retention(RetentionPolicy.RUNTIME) | |
| @interface SomeAnnots{ | |
| String author(); | |
| String date(); | |
| int currRev() default 1; | |
| String lastMod() default "N/a"; | |
| String lastModBy() default "N/a"; | |
| String[] reviewers(); | |
| } | |
| @SomeAnnots(author = "Class LasClas", date = "4/4/2025", reviewers = { "re1", "re2" }) | |
| class SomeAnn { | |
| /* | |
| public String SomeMeth() { | |
| Method m = Class.forName("Annot").getMethod("author"); | |
| Annot a = m.getAnnotation(Annot.class); | |
| String val = a.author(); | |
| System.out.println(); | |
| return ""; | |
| } | |
| */ | |
| } |
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