Java assign pro

How to assign default values to custom annotations

package com.java2novice.annotations;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.reflect.Method;

Retention(RetentionPolicy.Runtime)

interface MyAnnot

{

    String key() default "site";

    String value() default "java2novice.com";

}

public class MyAnnotDefaultValues

{

   MyAnnot()

    public void myAnnotationTestMethod()

{

    try

    {

            Class MyAnnotDefaultValues> cls = this.getClass();

            Method mth = cls.getMethod("myAnnotationTestMethod");

            MyAnnot myAnno = mth.getAnnotation(MyAnnot.class);

            System.out.println("key: "+myAnno.key());

            System.out.println("value: "+myAnno.value());

        }

         catch (SecurityException e)

          {

            e.printStackTrace();

          }

         catch (NoSuchMethodException e)

         {

            e.printStackTrace();

        }

    }

   public static void main(String a[])

  {

        MyAnnotDefaultValues mat = new MyAnnotDefaultValues();

        mat.myAnnotationTestMethod();

    }

}

What is marker annotation and how to process it at runtime

package com.java2novice.annotations;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.reflect.Method;

Retention(RetentionPolicy.Runtime)

interface MyMarkerAnnot{}

public class MyMarkerAnnotation

{

   MyMarkerAnnot

    public void myAnnotationTestMethod()

{

       try

     {

            Class MyMarkerAnnotation> cls = this.getClass();

            Method mth = cls.getMethod("myAnnotationTestMethod");

            if(mth.isAnnotationPresent(MyMarkerAnnot.class)){

                System.out.println("Hey... marker annotation is present.");

            }

            else

         {

                System.out.println("Marker annotation is not present.");

            }

        }

         catch (SecurityException e)

        {

            e.printStackTrace();

        }

        catch (NoSuchMethodException e)

        {

               e.printStackTrace();

        }

    }

    public static void main(String a[])

    {

        MyMarkerAnnotation mat = new MyMarkerAnnotation();

        mat.myAnnotationTestMethod();

    }

}

Built-in Java Annotations

package com.java2novice.annotations;

public class MyDeprecatedExmp

{

 public void showDeprecatedMessage()

{

        System.out.println("This method is marked as deprecated");

  }

 public static void main(String a[])

{

        MyDeprecatedExmp mde = new MyDeprecatedExmp();

        mde.showDeprecatedMessage();

    }

}

Built-in Java Annotations

package com.java2novice.annotations;

public class Animal

{

public void makeSound()

{

      }

}

class Cat extends Animal

{

 public void makeSound()

 {

        System.out.println("myyyyyaaawwwwww");

    }

}