75 lines
2.2 KiB
Java
75 lines
2.2 KiB
Java
// patterns/dynatrash/DynaTrash.java
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// (c)2020 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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// Using a Map of Lists and RTTI to automatically
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// sort trash into Lists. This solution, despite
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// the use of RTTI, is extensible.
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// {java patterns.dynatrash.DynaTrash}
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package patterns.dynatrash;
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import patterns.trash.*;
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import java.util.*;
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import java.util.stream.*;
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// Generic TypeMap works in any situation:
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class TypeMap<T> {
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private Map<Class,List<T>> t = new HashMap<>();
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public void add(T o) {
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Class type = o.getClass();
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if(t.containsKey(type))
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t.get(type).add(o);
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else {
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List<T> v = new ArrayList<>();
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v.add(o);
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t.put(type,v);
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}
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}
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public Stream<List<T>> values() {
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return t.values().stream();
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}
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}
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// Adapter class for callbacks
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// from ParseTrash.fillBin():
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class TypeMapAdapter implements Fillable {
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TypeMap<Trash> map;
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TypeMapAdapter(TypeMap<Trash> tm) {
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map = tm;
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}
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@Override
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public void addTrash(Trash t) { map.add(t); }
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}
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public class DynaTrash {
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@SuppressWarnings("unchecked")
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public static void main(String[] args) {
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TypeMap<Trash> bin = new TypeMap<>();
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ParseTrash.fillBin(
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"trash", new TypeMapAdapter(bin));
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bin.values().forEach(Trash::sumValue);
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}
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}
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/* Output: (First and Last 10 Lines)
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Loading patterns.trash.Glass
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Loading patterns.trash.Paper
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Loading patterns.trash.Aluminum
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Loading patterns.trash.Cardboard
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weight of patterns.trash.Paper = 22.0
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weight of patterns.trash.Paper = 11.0
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weight of patterns.trash.Paper = 88.0
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weight of patterns.trash.Paper = 91.0
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weight of patterns.trash.Paper = 80.0
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weight of patterns.trash.Paper = 66.0
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...________...________...________...________...
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weight of patterns.trash.Aluminum = 81.0
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weight of patterns.trash.Aluminum = 36.0
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weight of patterns.trash.Aluminum = 93.0
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weight of patterns.trash.Aluminum = 36.0
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Total value = 860.0499778985977
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weight of patterns.trash.Cardboard = 96.0
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weight of patterns.trash.Cardboard = 44.0
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weight of patterns.trash.Cardboard = 12.0
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weight of patterns.trash.Cardboard = 22.0
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Total value = 40.02000072598457
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*/
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