1. Explain the Java interface and its use in a few sentences.

2. Write the code of one Java interface with one method.

3. Also write two Java classes that will implement the method of this interface, but each class will implement this method from the interface differently. Simply put System.out.println inside each method with different output to demonstrate different implementation.

4. Write a few sentences explaining your code and the expected result/output.

Along with the course material, the following is a good read.