public interface Heater {
	public void heat();
	public void noHeat();
}

public interface Cooler {
	public void cool();
	public void noCool();
}

public interface Device {
	public void switchOn();
	public void switchOff();
}

public class DeviceImpl {
	public DeviceImpl(...) {...}
	public switchOn() {...}
	public switchoff() {...}
}

public class Heater {
	Device device;

	public Heater() {
		this.device = new DeviceImpl(...);
	}

	public void heat() {
		this.device.switchOn();
	}

	public void noHeat() {
		this.device.switchOff();
	}
}

public class Cooler {
	Device device;

	public Cooler() {
		this.device = new DeviceImpl(...);
	}

	public void cool() {
		this.device.switchOn();
	}

	public void noCool() {
		this.device.switchOff();
	}
}