#107 Double Dispatch example JavaDoc
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@ -8,23 +8,27 @@ import java.util.List;
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* When a message with a parameter is sent to an object, the resultant behaviour is defined by the
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* implementation of that method in the receiver. Sometimes the behaviour must also be determined
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* by the type of the parameter.
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*
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* <p>
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* One way to implement this would be to create multiple instanceof-checks for the methods parameter.
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* However, this creates a maintenance issue. When new types are added we would also need to change
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* the method's implementation and add a new instanceof-check. This violates the single responsibility
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* principle - a class should have only one reason to change.
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*
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* <p>
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* Instead of the instanceof-checks a better way is to make another virtual call on the parameter
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* object. This way new functionality can be easily added without the need to modify existing
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* implementation (open-closed principle).
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*
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* In this example we have hierarchy of objects (GameObject) that can collide to each other. Each
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* <p>
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* In this example we have hierarchy of objects ({@link GameObject}) that can collide to each other. Each
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* object has its own coordinates which are checked against the other objects' coordinates. If
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* there is an overlap, then the objects collide utilizing the Double Dispatch pattern.
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*
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*/
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public class App {
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/**
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* Program entry point
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* @param args command line args
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*/
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public static void main( String[] args ) {
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// initialize game objects and print their status
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List<GameObject> objects = new ArrayList<>();
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@ -4,6 +4,11 @@ import org.junit.Test;
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import com.iluwatar.doubledispatch.App;
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/**
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*
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* Application test
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*
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*/
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public class AppTest {
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@Test
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