public class Context {
  private State state;

  public Context(State state) {
    this.state = state;
  }
  public State getState() {
    return state;
  }
  public void setState(State state) {
    this.state = state;
  }

  public void request() {
    state.handle(this);
  }
  public void displayState() {
    System.out.println("状態は" + state.getClass().getName() + "です");
  }
}