[JAVA][Beginning Java 8 Games Development]

Chapter 10 ■ Directing the Cast of Actors: Creating a Casting Director Engine and Creating the Bagel Actor Class
So, if you had defined a Hero interface, and wanted to implement it in one of your classes, in which case the Java
compiler would watch over the code and make sure that you are implementing the necessary method structures, the
class definition line of code and the methods inside the body of the class would look something like the following:
public class SuperHero implements Hero {
protected boolean flagVariable1, flagVariable2;
public void update() {
// Java statements to process on each update
}
public boolean collide(Actor actor) {
// Java statements to process for collision detection
}
}
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So with the java.util ArrayList class that we looked at earlier, the technical class definition is as follows:
public class ArrayList extends AbstractList implements List
The ArrayList class also implements RandomAccess, Cloneable, and Serializable, but we will not be using
those at this time so I am just showing you the parts of the ArrayList class definition that pertain to what we will
be learning during this chapter, not the full public class ArrayList extends AbstractList implements
List, RandomAccess, Cloneable, Serializable class definition, as you would see if you look at the Java class
documentation for the ArrayList class online.
It is important to notice that the .addAll(), .removeAll() and .clear() method calls that we will use with the
ArrayList class are implemented because the List Java interface demands that they be implemented, so that is
the connection between the classes and why we will specify the declaration of the ArrayList object using this code:
private List CURRENT_CAST = new ArrayList();
You may be wondering why we will not need to explicitly specify the Actor object type on both sides of this
declaration and instantiation statement. Prior to Java 7, you would have needed to specify your Actor object type on
both sides of this statement, inside of the ArrayList() constructor method call. So, if you are writing game code that
needs to be compatible with Java 5 and Java 6, you would code this statement using the following line of Java code:
private List CURRENT_CAST = new ArrayList();
Now that we have learned what a Java interface is, let’s take a look at the List public interface in detail.
The List Public Interface: A List Collection of Java Objects
The List public interface is also a member of the Java Collections Framework. The Java public interface List
extends the Collections public interface, which extends the Iterable public interface. Thus, the super interface
to sub interface hierarchy would look something like this following List Java interface hierarchy:
Interface Iterable
> Interface Collection
> Interface List
A List is an ordered Collection and could also be thought of as a sequence of objects. In our case, the
List will be an ordered sequence of Actor objects. A user of the List interface has precise control over where in
the List each element (in our case, Actor object) is inserted. The user can access elements using an integer index, that
is, the position in the List, using a parenthesis after the name of the List. You can also search for elements in a List.
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