Questions and Exercises: Annotations

Questions

1. What is wrong with the following interface?

public interface House {
  @Deprecated
  void open();
  void openFrontDoor();
  void openBackDoor();
}

2. Compile this program:

interface Closable {
  void close();
}

class File implements Closable {
  @Override
  public void close() {
      //... close this file...
  }
}

What happens? Can you explain why?

3. 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 complains that open has been deprecated (in the interface). What can you do to get rid of that warning?

Check your answers.