Computational Problem Solving with Java and Interactive Object Graphics

Section 10.4 Key Concepts

1. An interface is a kind of contract to be fulfilled by a class definition.
2. An interface is made up of one or more method signatures.
3. A class implements an interface when it adds the implements keyword and an interface name to the start line of the class.
4. When a class implements an interface it is obligated to implement all methods signatures defined in that interface.
5. The compiler enforces the interface implementation contract. If the contract is not fulfilled completely, the compiler will fail with an error.
6. Interfaces may be defined using the angle brackets of generics, which allows methods signatures to be parameterized by type.
7. By implementing the java.lang.Comparable<T> Interface, objects may be sorted by Arrays.sort(…) or Collections.sort(…).
8. By implementing the java.util.Iterator<T> and java.util.Iterable<T> interfaces, objects may be iterated using the enhanced-for statement.
9. Polymorphism occurs when a single idea has many forms. There are multiple ways that Java supports polymorphism.
10. Polymorphic methods are implemented when multiple methods of the same name have distinct signatures
11. Polymorphic methods also occur when derived classes override base class methods
12. Polymorphic reference variables occur when a variable of type base class references a value of type derived class.
13. Polymorphic reference variables occur when a variable of type interface is capable of referencing any object that implements the interface.
14. Implementation inheritance in Java occurs when the extends keyword is used (is-a)
15. Interface inheritance in Java occurs when the implements keyword is used (another kind of is-a)