70 lines
1.9 KiB
Java
70 lines
1.9 KiB
Java
// generics/coffee/CoffeeSupplier.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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// {java generics.coffee.CoffeeSupplier}
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package generics.coffee;
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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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import java.lang.reflect.InvocationTargetException;
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public class CoffeeSupplier
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implements Supplier<Coffee>, Iterable<Coffee> {
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private Class<?>[] types = { Latte.class, Mocha.class,
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Cappuccino.class, Americano.class, Breve.class, };
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private static Random rand = new Random(47);
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public CoffeeSupplier() {}
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// For iteration:
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private int size = 0;
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public CoffeeSupplier(int sz) { size = sz; }
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@Override public Coffee get() {
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try {
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return (Coffee)
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types[rand.nextInt(types.length)]
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.getConstructor().newInstance();
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// Report programmer errors at runtime:
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} catch(InstantiationException |
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NoSuchMethodException |
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InvocationTargetException |
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IllegalAccessException e) {
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throw new RuntimeException(e);
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}
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}
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class CoffeeIterator implements Iterator<Coffee> {
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int count = size;
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@Override
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public boolean hasNext() { return count > 0; }
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@Override public Coffee next() {
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count--;
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return CoffeeSupplier.this.get();
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}
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@Override
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public void remove() { // Not implemented
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throw new UnsupportedOperationException();
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}
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}
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@Override public Iterator<Coffee> iterator() {
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return new CoffeeIterator();
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}
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public static void main(String[] args) {
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Stream.generate(new CoffeeSupplier())
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.limit(5)
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.forEach(System.out::println);
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for(Coffee c : new CoffeeSupplier(5))
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System.out.println(c);
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}
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}
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/* Output:
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Americano 0
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Latte 1
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Americano 2
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Mocha 3
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Mocha 4
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Breve 5
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Americano 6
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Latte 7
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Cappuccino 8
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Cappuccino 9
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*/
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