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Questions and Exercises: Creating Interfaces

Questions

1. What methods would a class that implements the java.util.Iterator interface have to implement?

2. What is wrong with the following interface?

public interface SomethingIsWrong {
    public void aMethod(int aValue){
        System.out.println("Hi Mom");
    }
}

3. Fix the interface in question 2.

4. Is the following interface valid?

public interface Marker {
}

Exercises

1. Write a class that implements the Iterator interface found in the java.util package. The ordered data for this exercise is the 13 cards in a suit from a deck of cards. The first call to next returns 2, the subsequent call returns the next highest card, 3, and so on, up to Ace. Write a small main method to test your class.

2. Suppose that you have written a time server, which periodically notifies its clients of the current date and time. Write an interface that the server could use to enforce a particular protocol on its clients.

Check your answers.

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