状态设计模式笔记

public interface State {
    public void doAction(Context context);
}

public class Context {
    private State state;
    public Context(){
        state=null;
    }

    public State getState() {
        return state;
    }

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

public class StartState implements State{
    @Override
    public void doAction(Context context) {
        System.out.println("start state");
        context.setState(this);
    }
    public String toString(){
        return "Start State";
    }
}

public class StopState implements State{
    @Override
    public void doAction(Context context) {
        System.out.println("stop state");
        context.setState(this);
    }
    public String toString(){
        return "Stop State";
    }
}

public class Test {
    public static void main(String[] args) {
        Context context=new Context();
        StartState start=new StartState();
        start.doAction(context);
        System.out.println(context.getState().toString());
        StopState stopState=new StopState();
        stopState.doAction(context);
        System.out.println(context.getState().toString());
    }


}