| New Interfaces |
| To create a new interface,we declare it like this: |
| public interface Growable { ... } |
| This is, effectively, the same as a class definition, with the word interface replacing the word class. Inside the interface definition we have methods and constants. |
| The method definitions inside the interface are public and abstract methods; We cannot declare a method inside an interface to be either private or protected. |
| So, for example, here's a Growable interface with one method explicitly declared public and abstract (growIt()) and one implicitly declared as such (growItBigger()) |
| public interface Growable { public abstract void growIt(); //explicity public and abstract void growItBigger(); // effectively public and abstract } |
| In addition to methods, interfaces can also have variables, but those variables must be declared public, static, and final (making them constant). |
| As with methods, we can explicitly define a variable to be public, static, and final. |
| Here's that same Growable definition with two new variables: |
| public interface Growable { public static final int increment = 10; long maxnum = 1000000; // becomes public static and final public abstract void growIt(); //explicitly public and abstract void growItBigger(); // effectively public and abstract } |
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