124 lines
3.7 KiB
Java
124 lines
3.7 KiB
Java
// patterns/recyclea/RecycleA.java
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// ©2016 MindView LLC: see Copyright.txt
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// Recycling with RTTI.
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package patterns.recyclea;
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import java.util.*;
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import java.util.function.*;
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import java.util.stream.*;
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abstract class Trash {
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double weight;
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Trash(double wt) { weight = wt; }
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abstract double value();
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// Sums the value of Trash in a bin:
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private static double val;
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static void sumValue(List<? extends Trash> bin) {
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val = 0.0f;
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bin.forEach( t -> {
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// Polymorphism in action:
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val += t.weight * t.value();
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System.out.println(
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"weight of " +
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// Using RTTI to get type
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// information about the class:
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t.getClass().getSimpleName() +
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" = " + t.weight);
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});
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System.out.println("Total value = " + val);
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}
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}
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class Aluminum extends Trash {
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static double val = 1.67f;
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Aluminum(double wt) { super(wt); }
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@Override
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double value() { return val; }
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static void value(double newval) {
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val = newval;
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}
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}
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class Paper extends Trash {
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static double val = 0.10f;
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Paper(double wt) { super(wt); }
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@Override
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double value() { return val; }
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static void value(double newval) {
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val = newval;
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}
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}
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class Glass extends Trash {
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static double val = 0.23f;
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Glass(double wt) { super(wt); }
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@Override
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double value() { return val; }
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static void value(double newval) {
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val = newval;
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}
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}
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class TrashFactory {
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static List<Function<Double, Trash>> ttypes =
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Arrays.asList(
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Aluminum::new, Paper::new, Glass::new);
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final static int sz = ttypes.size();
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private static Random rand = new Random(47);
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public static Trash newTrash() {
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return ttypes
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.get(rand.nextInt(sz))
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.apply(rand.nextDouble());
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}
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}
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public class RecycleA {
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public static void main(String[] args) {
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List<Trash> bin =
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Stream.generate(TrashFactory::newTrash)
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.limit(25)
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.collect(Collectors.toList());
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List<Glass> glassBin = new ArrayList<>();
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List<Paper> paperBin = new ArrayList<>();
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List<Aluminum> alBin = new ArrayList<>();
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// Sort the Trash:
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bin.forEach( t -> {
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// RTTI to discover Trash type:
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if(t instanceof Aluminum)
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alBin.add((Aluminum)t);
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if(t instanceof Paper)
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paperBin.add((Paper)t);
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if(t instanceof Glass)
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glassBin.add((Glass)t);
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});
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Trash.sumValue(alBin);
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Trash.sumValue(paperBin);
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Trash.sumValue(glassBin);
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Trash.sumValue(bin);
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}
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}
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/* Output: (First and last 11 Lines)
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weight of patterns.recyclea.Aluminum = 0.11435456649761422
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weight of patterns.recyclea.Aluminum = 0.5295954256745989
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weight of patterns.recyclea.Aluminum = 0.44032876173820623
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weight of patterns.recyclea.Aluminum = 0.483968447804611
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weight of patterns.recyclea.Aluminum = 0.2724064060083268
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weight of patterns.recyclea.Aluminum = 0.7661553155473436
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weight of patterns.recyclea.Aluminum = 0.32266202529378485
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weight of patterns.recyclea.Aluminum = 0.29010681217024337
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weight of patterns.recyclea.Aluminum = 0.04867885164993724
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weight of patterns.recyclea.Aluminum = 0.6398064631177899
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Total value = 6.526465168373229
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________...________...________...________...________
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weight of patterns.recyclea.Paper = 0.7024254510631527
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weight of patterns.recyclea.Paper = 0.7775491010186331
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weight of patterns.recyclea.Paper = 0.5929413550962656
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weight of patterns.recyclea.Paper = 0.8991222558891441
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weight of patterns.recyclea.Aluminum = 0.32266202529378485
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weight of patterns.recyclea.Aluminum = 0.29010681217024337
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weight of patterns.recyclea.Glass = 0.42812712031823896
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weight of patterns.recyclea.Paper = 0.8242175461669214
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weight of patterns.recyclea.Aluminum = 0.04867885164993724
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weight of patterns.recyclea.Aluminum = 0.6398064631177899
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Total value = 7.489772197549787
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*/
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