Head First 设计模式 --10 状态模式

interface State {

  public void insertQuarter();

  public void ejectQuarter();

  public void turnCrank();

  public void dispense();
}

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.hasQuarterState);
  }

  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";
  }
}

class HasQuarterState implements State {
  Random randomWinner = new Random(System.currentTimeMillis());
  GumballMachine gumballMachine;

  public HasQuarterState(GumballMachine gumballMachine) {
    this.gumballMachine = gumballMachine;
  }

  public void insertQuarter() {
    System.out.println("You can‘t insert another quarter");
  }

  public void ejectQuarter() {
    System.out.println("Quarter returned");
    gumballMachine.setState(gumballMachine.noQuarterState);
  }

  public void turnCrank() {
    System.out.println("You turned...");

    int winner = randomWinner.nextInt(10);
    if ((winner == 0) && (gumballMachine.count > 1)) {
      gumballMachine.setState(gumballMachine.winnerState);
    } else {
      gumballMachine.setState(gumballMachine.soldOutState);
    }
  }

  public void dispense() {
    System.out.println("No gumball dispensed");
  }

  public String toString() {
    return "waiting for turn of crank";
  }
}

class GumballMachine {
  State soldOutState;
  State noQuarterState;
  State hasQuarterState;
  State soldState;
  State winnerState;

  State state = soldOutState;
  int count = 0;

  public GumballMachine(int numberGumballs) {// soldOutState = new SoldOutState(this);
    noQuarterState = new NoQuarterState(this);
    hasQuarterState = new HasQuarterState(this);
    // soldState = new SoldState(this);
    // winnerState = new WinnerState(this);

    this.count = numberGumballs;
    if (numberGumballs > 0) {
      state = noQuarterState;
    }
  }

  public void insertQuarter() {
    state.insertQuarter();
  }

  public void ejectQuarter() {
    state.ejectQuarter();
  }

  public void turnCrank() {
    state.turnCrank();
    state.dispense();
  }

  void setState(State state) {
    this.state = state;
  }

  void releaseBall() {
    System.out.println("A gumball comes rolling out the slot...");
    if (count != 0) {
      count = count - 1;
    }
  }

}

public class StateTest {
  public static void main(String[] args) {
    GumballMachine gumballMachine = new GumballMachine(10);

    gumballMachine.insertQuarter();
    gumballMachine.turnCrank();
    gumballMachine.insertQuarter();
    gumballMachine.turnCrank();
  }
}