Test3.java

// Perverse test of ObservableSet - bottom of Page 267
package org.effectivejava.examples.chapter10.item67;

import java.util.HashSet;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Test3 {
	public static void main(String[] args) {
		ObservableSet<Integer> set = new ObservableSet<Integer>(
				new HashSet<Integer>());

		// Observer that uses a background thread needlessly
		set.addObserver(new SetObserver<Integer>() {
			public void added(final ObservableSet<Integer> s, Integer e) {
				System.out.println(e);
				if (e == 23) {
					ExecutorService executor = Executors
							.newSingleThreadExecutor();
					final SetObserver<Integer> observer = this;
					try {
						executor.submit(new Runnable() {
							public void run() {
								s.removeObserver(observer);
							}
						}).get();
					} catch (ExecutionException ex) {
						throw new AssertionError(ex.getCause());
					} catch (InterruptedException ex) {
						throw new AssertionError(ex.getCause());
					} finally {
						executor.shutdown();
					}
				}
			}
		});

		for (int i = 0; i < 100; i++)
			set.add(i);
	}
}