74 lines
1.8 KiB
Java
74 lines
1.8 KiB
Java
//: patterns/ShapeFactory2.java
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// ©2015 MindView LLC: see Copyright.txt
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// Polymorphic factory methods.
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import java.util.*;
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import java.util.function.*;
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import static net.mindview.util.Print.*;
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class BadShapeCreation extends Exception {
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BadShapeCreation(String msg) {
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super(msg);
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}
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}
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interface Shape {
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void draw();
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void erase();
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}
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abstract class ShapeFactory {
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static Map<String, Supplier<Shape>> factories =
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new HashMap<>();
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static Shape createShape(String id)
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throws BadShapeCreation {
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if(!factories.containsKey(id)) {
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try {
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Class.forName(id); // Load dynamically
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} catch(ClassNotFoundException e) {
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throw new BadShapeCreation(id);
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}
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// See if it was put in:
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if(!factories.containsKey(id))
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throw new BadShapeCreation(id);
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}
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return factories.get(id).get();
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}
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}
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class Circle implements Shape {
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private Circle() {}
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public void draw() { print("Circle.draw"); }
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public void erase() { print("Circle.erase"); }
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static {
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ShapeFactory.factories.put("Circle", Circle::new);
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}
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}
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class Square implements Shape {
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private Square() {}
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public void draw() { print("Square.draw"); }
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public void erase() { print("Square.erase"); }
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static {
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ShapeFactory.factories.put("Square", Square::new);
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}
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}
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public class ShapeFactory2 {
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public static void main(String args[]) {
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String shlist[] = { "Circle", "Square",
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"Square", "Circle", "Circle", "Square" };
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ArrayList<Shape> shapes = new ArrayList<>();
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try {
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for(String shlist1 : shlist) {
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shapes.add(
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ShapeFactory.createShape(shlist1));
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}
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} catch(BadShapeCreation e) {
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e.printStackTrace();
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return;
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}
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shapes.forEach(Shape::draw);
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shapes.forEach(Shape::erase);
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}
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} ///:~
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