SourceMaking

import java.util.*;

public class CommandQueue {

 

interface Command { void execute(); }

 

static class DomesticEngineer implements Command {

   public void execute() {

      System.out.println( "take out the trash" );

}  }

 

static class Politician implements Command {

   public void execute() {

      System.out.println( "take money from the rich, take votes from the poor" );

}  }

 

static class Programmer implements Command {

   public void execute() {

      System.out.println( "sell the bugs, charge extra for the fixes" );

}  }

 

public static List produceRequests() {

   List queue = new ArrayList();

   queue.add( new DomesticEngineer() );

   queue.add( new Politician() );

   queue.add( new Programmer() );

   return queue;

}

 

public static void workOffRequests( List queue ) {

   for (Iterator it = queue.iterator(); it.hasNext(); )

      ((Command)it.next()).execute();

}

 

public static void main( String[] args ) {

   List queue = produceRequests();

   workOffRequests( queue );

}}