51 lines
1.4 KiB
Java
51 lines
1.4 KiB
Java
// collections/AdapterMethodIdiom.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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// The "Adapter Method" idiom uses for-in
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// with additional kinds of Iterables
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import java.util.*;
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class ReversibleArrayList<T> extends ArrayList<T> {
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ReversibleArrayList(Collection<T> c) {
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super(c);
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}
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public Iterable<T> reversed() {
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return new Iterable<T>() {
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public Iterator<T> iterator() {
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return new Iterator<T>() {
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int current = size() - 1;
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@Override public boolean hasNext() {
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return current > -1;
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}
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@Override
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public T next() { return get(current--); }
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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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}
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};
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}
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}
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public class AdapterMethodIdiom {
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public static void main(String[] args) {
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ReversibleArrayList<String> ral =
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new ReversibleArrayList<>(
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Arrays.asList("To be or not to be".split(" ")));
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// Grabs the ordinary iterator via iterator():
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for(String s : ral)
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System.out.print(s + " ");
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System.out.println();
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// Hand it the Iterable of your choice
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for(String s : ral.reversed())
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System.out.print(s + " ");
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}
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}
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/* Output:
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To be or not to be
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be to not or be To
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*/
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