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// collections/AdapterMethodIdiom.java

// (c)2021 MindView LLC: see Copyright.txt

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

// The "Adapter Method" idiom uses for-in

// with additional kinds of Iterables

import java.util.*;

class ReversibleArrayList<T> extends ArrayList<T> {

ReversibleArrayList(Collection<T> c) {

super(c);

}

public Iterable<T> reversed() {

return new Iterable<T>() {

public Iterator<T> iterator() {

return new Iterator<T>() {

int current = size() - 1;

@Override public boolean hasNext() {

return current > -1;

}

@Override

public T next() { return get(current--); }

@Override

public void remove() { // Not implemented

throw new UnsupportedOperationException();

}

};

}

};

}

}

public class AdapterMethodIdiom {

public static void main(String[] args) {

ReversibleArrayList<String> ral =

new ReversibleArrayList<>(

Arrays.asList("To be or not to be".split(" ")));

// Grabs the ordinary iterator via iterator():

for(String s : ral)

System.out.print(s + " ");

System.out.println();

// Hand it the Iterable of your choice

for(String s : ral.reversed())

System.out.print(s + " ");

}

}

/* Output:

To be or not to be

be to not or be To

*/