Design Pattern(7) - State

public void insertQuarter() {
    if (state == HAS_QUARTER) {
	System.out.println("You can't insert another quarter");
    } else if (state == NO_QUARTER) {
	state = HAS_QUARTER;
    	System.out.println("You inserted a quarter");
    } else if (state == SOLD_OUT) {
    	System.out.println("You can't insert a quarter, the machine is sold out");
    } else if (state == SOLD) {
      	System.out.println("Please wait, we're already giving you a gumball");
    }
}

public void turnCrank() {
    if (state == SOLD) {
	System.out.println("Turning twice doesn't get you another gumball!");
    } else if (state == NO_QUARTER) {
	System.out.println("You turned but there's no quarter");
    } else if (state == SOLD_OUT) {
	System.out.println("You turned, but there are no gumballs");
    } else if (state == HAS_QUARTER) {
	System.out.println("You turned...");
	state = SOLD;
	dispense();
    }
}

public interface State {
    public void insertQuarter();
    public void ejectQuarter();
    public void turnCrank();
    public void dispense();
}

public class NoQuarterState implements State {
    GumballMachine gumballMachine;
    public NoQuarterState(GumballMachine gumballMachine) {
        this.gumballMachine = gumballMachine;
    }
    public void insertQuarter() {
	System.out.println("You inserted a quarter");
	gumballMachine.setState(gumballMachine.getHasQuarterState());
    }
    public void ejectQuarter() {
	System.out.println("You haven't inserted a quarter");
    }
    public void turnCrank() {
	System.out.println("You turned, but there's no quarter");
    }
    public void dispense() {
	System.out.println("You need to pay first");
    } 
    public String toString() {
  	return "waiting for quarter";
    }
}