96 lines
2.3 KiB
Java
96 lines
2.3 KiB
Java
//: patterns/recyclea/RecycleA.java
|
|
// ©2015 MindView LLC: see Copyright.txt
|
|
// Recycling with RTTI.
|
|
package patterns.recyclea;
|
|
import java.util.*;
|
|
|
|
abstract class Trash {
|
|
private double weight;
|
|
Trash(double wt) { weight = wt; }
|
|
abstract double value();
|
|
double weight() { return weight; }
|
|
// Sums the value of Trash in a bin:
|
|
static void sumValue(List<? extends Trash> bin) {
|
|
double val = 0.0f;
|
|
for(Trash t : bin) {
|
|
// Polymorphism in action:
|
|
val += t.weight() * t.value();
|
|
System.out.println(
|
|
"weight of " +
|
|
// Using RTTI to get type
|
|
// information about the class:
|
|
t.getClass().getName() +
|
|
" = " + t.weight());
|
|
}
|
|
System.out.println("Total value = " + val);
|
|
}
|
|
}
|
|
|
|
class Aluminum extends Trash {
|
|
static double val = 1.67f;
|
|
Aluminum(double wt) { super(wt); }
|
|
@Override
|
|
double value() { return val; }
|
|
static void value(double newval) {
|
|
val = newval;
|
|
}
|
|
}
|
|
|
|
class Paper extends Trash {
|
|
static double val = 0.10f;
|
|
Paper(double wt) { super(wt); }
|
|
@Override
|
|
double value() { return val; }
|
|
static void value(double newval) {
|
|
val = newval;
|
|
}
|
|
}
|
|
|
|
class Glass extends Trash {
|
|
static double val = 0.23f;
|
|
Glass(double wt) { super(wt); }
|
|
@Override
|
|
double value() { return val; }
|
|
static void value(double newval) {
|
|
val = newval;
|
|
}
|
|
}
|
|
|
|
public class RecycleA {
|
|
public static void main(String[] args) {
|
|
List<Trash> bin = new ArrayList<>();
|
|
// Fill up the Trash bin:
|
|
for(int i = 0; i < 30; i++)
|
|
switch((int)(Math.random() * 3)) {
|
|
case 0 :
|
|
bin.add(new
|
|
Aluminum(Math.random() * 100));
|
|
break;
|
|
case 1 :
|
|
bin.add(new
|
|
Paper(Math.random() * 100));
|
|
break;
|
|
case 2 :
|
|
bin.add(new
|
|
Glass(Math.random() * 100));
|
|
}
|
|
List<Glass> glassBin = new ArrayList<>();
|
|
List<Paper> paperBin = new ArrayList<>();
|
|
List<Aluminum> alBin = new ArrayList<>();
|
|
// Sort the Trash:
|
|
for(Trash t : bin) {
|
|
// RTTI to discover Trash type:
|
|
if(t instanceof Aluminum)
|
|
alBin.add((Aluminum)t);
|
|
if(t instanceof Paper)
|
|
paperBin.add((Paper)t);
|
|
if(t instanceof Glass)
|
|
glassBin.add((Glass)t);
|
|
}
|
|
Trash.sumValue(alBin);
|
|
Trash.sumValue(paperBin);
|
|
Trash.sumValue(glassBin);
|
|
Trash.sumValue(bin);
|
|
}
|
|
} ///:~
|