JAVA - Annotation

@Target({ElementType.METHOD})
 @Retention(RetentionPolicy.RUNTIME)
 public @interface TODO {
     int priority() default 0;
 }

@Target({ElementType.FIELD})
 @Retention(RetentionPolicy.RUNTIME)
 public @interface TOFORMATE {
 }

public class MyCalculator {
     boolean isReady;
         @TOFORMATE double concurrency;
     @TOFORMATE Date debitDate;
     public MyCalculator() {
     super();
     }

     @TODO
     public void calculateRate(){
         System.out.println("Calculating...");
     }
 }

public class TestCalculator {
     public static void main(String[] args) {
         MyCalculator cal = new MyCalculator();
         cal.calculateRate();
     try {
         Class c = cal.getClass();
         Method[] methods = c.getDeclaredMethods();

             for (Method m: methods) {
         // 判断这个方法有没有使用 TODO
         if (m.isAnnotationPresent(TODO.class))
         System.out.println("Method "+m.getName()+": the TODO is present");
         }

         Field[] fields = c.getDeclaredFields();
         for (Field f : fields) {
         // 判断这个域有没有使用 TOFORMATE
             if (f.isAnnotationPresent(TOFORMATE.class))
             System.out.println("Field "+f.getName()+": the TOFORMATE is present");
             }
         } catch (Exception exc) {
             exc.printStackTrace();
         }
     }
}