54 lines
1.3 KiB
Java
54 lines
1.3 KiB
Java
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// enumerations/Shapes.java
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// (c)2021 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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// {NewFeature} Preview in JDK 17
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// Compile with javac flags:
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// --enable-preview --source 17
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// Run with java flag: --enable-preview
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import java.util.*;
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sealed interface Shape {
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double area();
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}
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record Circle(double radius) implements Shape {
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@Override public double area() {
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return Math.PI * radius * radius;
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}
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}
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record Rectangle(double side1, double side2)
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implements Shape {
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@Override public double area() {
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return side1 * side2;
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}
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}
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public class Shapes {
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static void classify(Shape s) {
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System.out.println(switch(s) {
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case Circle c && c.area() < 100.0
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-> "Small Circle: " + c;
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case Circle c -> "Large Circle: " + c;
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case Rectangle r && r.side1() == r.side2()
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-> "Square: " + r;
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case Rectangle r -> "Rectangle: " + r;
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});
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}
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public static void main(String[] args) {
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List.of(
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new Circle(5.0),
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new Circle(25.0),
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new Rectangle(12.0, 12.0),
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new Rectangle(12.0, 15.0)
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).forEach(t -> classify(t));
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}
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}
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/* Output:
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Small Circle: Circle[radius=5.0]
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Large Circle: Circle[radius=25.0]
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Square: Rectangle[side1=12.0, side2=12.0]
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Rectangle: Rectangle[side1=12.0, side2=15.0]
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*/
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