// The MIT License (MIT)

//

// Copyright (c) 2018 Robert C. Seacord

//

// Permission is hereby granted, free of charge, to any person obtaining a copy

// of this software and associated documentation files (the "Software"), to deal

// in the Software without restriction, including without limitation the rights

// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

// copies of the Software, and to permit persons to whom the Software is

// furnished to do so, subject to the following conditions:

//

// The above copyright notice and this permission notice shall be included in all

// copies or substantial portions of the Software.

//

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

// SOFTWARE.

//

package exp06j;

import java.util.concurrent.ThreadLocalRandom;

class ReadCommand implements Command {

@Override

public void execute() {

System.out.println("Read");

}

}

class WriteCommand implements Command {

@Override

public void execute() {

System.out.println("Write");

}

}

// Sleeps when executed

class SleepCommand implements Command {

@Override

public void execute() throws InterruptedException {

System.out.println("Sleep");

Thread.sleep(1000);

}

}

public class CommandFactory {

public Command getCommand() {

if (ThreadLocalRandom.current().nextBoolean()) {

return new ReadCommand();

}

else if (ThreadLocalRandom.current().nextBoolean()) {

return new WriteCommand();

}

// special case: no command ready to be completed

else {

return null;

// return new SleepCommand();

}

}

} // end class CommandFactory

class Program {

public static void main(String[] args) throws InterruptedException {

CommandFactory factory = new CommandFactory();

//noinspection InfiniteLoopStatement

while (true) {

Command command = factory.getCommand();

// Since the CommandFactory can return null commands,

// clients are obligated to check if the command received

// is null and if it is, sleep for 1 second.

if (command != null) {

command.execute();

}

else {

System.out.println("Sleep");

Thread.sleep(1000);

}

}

}

}