Trail: Learning the Java Language
Lesson: Annotations
Questions and Exercises
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Questions and Exercises: Annotations

Questions

  1. What is wrong with the following interface?

    public interface House {
        @Deprecated
        void open();
        void openFrontDoor();
        void openBackDoor();
    }
    
  2. Consider this implementation of the House interface, shown in Question 1.

    public class MyHouse implements House {
        public void open() {}
        public void openFrontDoor() {}
        public void openBackDoor() {}
    }
    

    If you compile this program, the compiler produces an error because open was deprecated (in the interface). What can you do to get rid of that warning?

  3. Will the following code compile without error? Why or why not?

    public @interface Meal { ... }
    
    @Meal("breakfast", mainDish="cereal")
    @Meal("lunch", mainDish="pizza")
    @Meal("dinner", mainDish="salad")
    public void evaluateDiet() { ... }
    

Exercises

  1. Define an annotation type for an enhancement request with elements id, synopsis, engineer, and date. Specify the default value as unassigned for engineer and unknown for date.

Check your answers.


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