gistfile1.java

public class ChainingExample {

  private final Executor mainPool;
  private final Executor ioPool;

  public ChainingExample(Executor mainPool, Executor ioPool) {
    this.mainPool = mainPool;
    this.ioPool = ioPool;
  }

  public ListenableFuture<File> getMergedFileForUser(String user) throws Exception {
    ListenableFuture<List<String>> files = getFilesForUser("dave");
    ListenableFuture<List<URL>> urls = 
      Futures.transform(files, locateFiles(), mainPool);
    ListenableFuture<List<File>> downloadedFiles = 
      Futures.transform(urls, downloadFiles(), mainPool);
    return Futures.transform(downloadedFiles, mergeFiles(), ioPool);
  }

  ListenableFuture<List<String>> getFilesForUser(String user) { ... }

  AsyncFunction<List<String>, List<URL>> locateFiles() { ... }

  AsyncFunction<List<URL>, List<File>> downloadFiles() { ... }

  AsyncFunction<List<File>, File> mergeFiles() { ... }

}