GumballMachine.java

package StatePattern.FirstTry;

public class GumballMachine {
    final static int SOLD_OUT = 0;
    final static int NO_QUARTER = 1;
    final static int HAS_QUARTER = 2;
    final static int SOLD = 3;

    int status = SOLD_OUT;
    int count = 0;

    public GumballMachine(int count){
        this.count = count;
        if(count >0){
            status = NO_QUARTER;
        }
    }

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

    public void ejectQuarter(){
        if(status == HAS_QUARTER){
            System.out.println("Quarter returned");
            status = NO_QUARTER;
        } else if(status == NO_QUARTER){
            System.out.println("You haven't inserted a quarter");
        } else if(status == SOLD){
            System.out.println("Sorry, you already turned the crank");
        } else if(status == SOLD_OUT){
            System.out.println("You can't eject, you haven't inserted a quarter yet");
        }
    }
    
    public void turnCrank(){
        if(status == SOLD){
            System.out.println("Turning twice doesn't get you another gumball!");
        } else if(status == NO_QUARTER){
            System.out.println("You turned but there's no quarter");
        } else if(status == SOLD_OUT){
            System.out.println("You turned, but there are no gumballs");
        } else if(status == HAS_QUARTER){
            System.out.println("You turned...");
            status = SOLD;
            dispense();
        }
    }

    public void dispense(){
        if(status == SOLD){
            System.out.println("A gumball comes rolling out the slot");
            count = count -1;
            if(count == 0){
                System.out.println("Oops, out of gumballs!");
                status = SOLD_OUT;
            } else {
                status = NO_QUARTER;
            }
        } else if(status == NO_QUARTER){
            System.out.println("You need to pay first");
        } else if(status == SOLD_OUT){
            System.out.println("No gumball dispensed");
        } else if(status == HAS_QUARTER){
            System.out.println("No gumball dispensed");
        }
    }

    public void refill(int numGumballs) {
        this.count += numGumballs;
        if (count > 0) {
            status = NO_QUARTER;
        }
        System.out.println("Refilled with " + numGumballs + " gumballs");
    }

    public String toString() {
        StringBuffer result = new StringBuffer();
        result.append("\nMighty Gumball, Inc.");
        result.append("\nJava-enabled Standing Gumball Model #2004\n");
        result.append("Inventory: " + count + " gumball");
        if (count != 1) {
            result.append("s");
        }
        result.append("\nMachine is ");
        if (status == SOLD_OUT) {
            result.append("sold out");
        } else if (status == NO_QUARTER) {
            result.append("waiting for quarter");
        } else if (status == HAS_QUARTER) {
            result.append("waiting for turn of crank");
        } else if (status == SOLD) {
            result.append("delivering a gumball");
        }
        result.append("\n");
        return result.toString();
    }
}