DesignVendingMachine.java

package Solutions;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

class MachineWarning extends Exception {

	public MachineWarning(String string) {
		// TODO Auto-generated constructor stub
	}

	public String getMessage() {
		System.out.println("error");
		return null;
	}
}

class VendingMachine {
	State coninInsertedState = new CoinInsertedState(this);
	State emptyState = new EmptyState(this);
	State noCoinInsertedState = new NoCoinInsertedState(this);
	State dispensingState = new DispensingState(this);
	State machineState = null;
	int capacity = 0;

	public VendingMachine() {
		machineState = noCoinInsertedState;
	}

	public void reFill(int count) {
		capacity += count;
		machineState = noCoinInsertedState;
	}

	/**
	 * Two Actions performed by MAchine
	 */
	public void insertCoin() throws MachineWarning {
		machineState.insertCoin();
	}

	public void pressButton() throws MachineWarning {
		machineState.pressButton();
		machineState.dispense();
		capacity--;
	}

	public boolean isEmpty() {
		if (capacity <= 0)
			return true;
		else
			return false;
	}

	public void setMachineState(State machineState) {
		this.machineState = machineState;
	}

	public State getMachineState() {
		return machineState;
	}

	public void setConinInsertedState(State coninInsertedState) {
		this.coninInsertedState = coninInsertedState;
	}

	public State getConinInsertedState() {
		return coninInsertedState;
	}

	public void setEmptyState(State emptyState) {
		this.emptyState = emptyState;
	}

	public State getEmptyState() {
		return emptyState;
	}

	public void setNoCoinInsertedState(State noCoinInsertedState) {
		this.noCoinInsertedState = noCoinInsertedState;
	}

	public State getNoCoinInsertedState() {
		return noCoinInsertedState;
	}

	public void setDispensingState(State dispensingState) {
		this.dispensingState = dispensingState;
	}

	public State getDispensingState() {
		return dispensingState;
	}

	public void setCapacity(int capacity) {
		this.capacity = capacity;
	}

	public int getCapacity() {
		return capacity;
	}
}

interface State {

	public void insertCoin() throws MachineWarning;

	public void pressButton() throws MachineWarning;

	public void dispense() throws MachineWarning;
}

class CoinInsertedState implements State {
	VendingMachine machine = null;

	public CoinInsertedState(VendingMachine machine) {
		this.machine = machine;
	}

	public void insertCoin() throws MachineWarning {
		throw new MachineWarning("Coin is already inserted.");
	}

	public void dispense() throws MachineWarning {
		throw new MachineWarning("Dispense button is not pressed.");

	}

	public void pressButton() throws MachineWarning {
		machine.setMachineState(machine.getDispensingState());
	}
}

class DispensingState implements State {
	VendingMachine machine;

	DispensingState(VendingMachine machine) {
		this.machine = machine;
	}

	public void insertCoin() throws MachineWarning {
		throw new MachineWarning("wait ... previous order is processing");
	}

	public void pressButton() throws MachineWarning {
		throw new MachineWarning("wait ... previous order is processing");
	}

	public void dispense() throws MachineWarning {
		machine.setMachineState(machine.getNoCoinInsertedState());
	}
}

class EmptyState implements State {
	VendingMachine machine;

	public EmptyState(VendingMachine machine) {
		this.machine = machine;
	}

	public void insertCoin() throws MachineWarning {
		throw new MachineWarning("Can not process the request");
	}

	public void pressButton() throws MachineWarning {
		throw new MachineWarning("Invalid Action");
	}

	public void dispense() throws MachineWarning {
		throw new MachineWarning("Invalid Action");
	}
}

class NoCoinInsertedState implements State {
	VendingMachine machine;

	public NoCoinInsertedState(VendingMachine machine) {
		this.machine = machine;
	}

	public void insertCoin() throws MachineWarning {
		if (!machine.isEmpty()) {
			machine.setMachineState(machine.getConinInsertedState());
		} else {
			throw new MachineWarning("Can not process request .. Machine is out of stock");
		}
	}

	public void pressButton() throws MachineWarning {
		throw new MachineWarning("No coin inserted ..");
	}

	public void dispense() throws MachineWarning {
		throw new MachineWarning("Invalid Operation");
	}
}

public class DesignVendingMachine {
	public DesignVendingMachine() {

	}

	public static void main(String[] args) {
		VendingMachine machine = new VendingMachine();
		machine.reFill(2); //
		// First despense
		try {
			machine.insertCoin();
			machine.pressButton();
		} catch (MachineWarning e) {
			System.out.println("Test 1:" + e.getMessage());
		}
		// Second Test
		try {
			machine.insertCoin();
			machine.insertCoin();
			machine.pressButton();
		} catch (MachineWarning e) {
			System.out.println("Test 2:" + e.getMessage());
			try {
				machine.pressButton();
			} catch (MachineWarning f) {
				// TODO
			}
		}
		// Test THree
		try {
			machine.pressButton();
		} catch (MachineWarning e) {
			System.out.println("Test 3:" + e.getMessage());
		}
		// Test Four
		try {
			machine.insertCoin();
		} catch (MachineWarning e) {
			System.out.println("Test 4:" + e.getMessage());
		}

	}

}