黑马程序员 7k面试题 交通灯管理系统

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面向对象的分析和设计

（重要思想）

谁拥有该数据，谁就对外提供操作这些数据的方法。  

eg:

人在黑板上画图

person,blackboard,circle

draw(){

x,y-->radius

}

两块石头磨成一把石刀，石刀可以砍树，砍成木材，木材做成椅子

KnifeFactory.createKnife(Stone stone1,Stone stone2)

Stone

StoneKnife

tree

material = StoneKnife.cut(tree)

chair = ChairFactory.makeChair(material)

球从一根绳子的一端移动到另一端

绳子是用来提供小球移动的（所以~~绳子拥有数据，就得提供这些数据的方法）

class Rope{

private Point start;

private Point end;

public Rope(Point start,Point end){

this.start = start;

this.end = end;

}

public Point nextPoint(Point currentPoint){//提供数据方法

^

}

}

class Ball{

private Rope rope;

private Point currentPoint;

public Ball(Rope rope,startPoint){

this.rope = rope;

this.currentPoint = startPoint;

}

public void move(){

currentPoint = rope.nextPoint(currentPoint);

System.out.println("小球移动了"+currentPoint);

}

}

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思路分析：路上存在一个集合，集合里装着车，看红绿灯减少车；

12个灯，拐弯的灯是常亮的——枚举

public enum Lamp {

S2N("N2S","S2W",false),S2W("N2E","E2W",false),E2W("W2E","E2S",false),E2S("W2N","S2N",false),

N2S(null,null,false),N2E(null,null,false),W2E(null,null,false),W2N(null,null,false),

S2E(null,null,true),E2N(null,null,true),N2W(null,null,true),W2S(null,null,true);

private Lamp(String opposite,String next,boolean lighted){

this.opposite = opposite;

this.next = next;   

this.lighted = lighted;

}

private boolean lighted;

private String opposite;

private String next;

public boolean isLighted(){

return lighted;

}

public void light(){

this.lighted = true;

if(opposite != null){

Lamp.valueOf(opposite).light();

}

System.out.println(name() + " lamp is green，下面总共应该有6个方向能看到汽车穿过！");

}

public Lamp blackOut(){

this.lighted = false;

if(opposite != null){

Lamp.valueOf(opposite).blackOut();

}

Lamp nextLamp= null;

if(next != null){

nextLamp = Lamp.valueOf(next);

System.out.println("绿灯从" + name() + "-------->切换为" + next);

nextLamp.light();

}

return nextLamp;

}

}

------------------------------------------------------------------------------------

控制器

public class LampController {

private Lamp currentLamp;

public LampController(){

//刚开始让由南向北的灯变绿;

currentLamp = Lamp.S2N;

currentLamp.light();

ScheduledExecutorService timer =  Executors.newScheduledThreadPool(1);

timer.scheduleAtFixedRate(

new Runnable(){

public  void run(){

System.out.println("来啊"); 

currentLamp = currentLamp.blackOut();

}

},

10,

10,

TimeUnit.SECONDS);

}

}

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主函数

public class MainClass {

public static void main(String[] args) {

String [] directions = new String[]{

"S2N","S2W","E2W","E2S","N2S","N2E","W2E","W2N","S2E","E2N","N2W","W2S"

};

for(int i=0;i

new Road(directions[i]);

}

new LampController();

}

}

------------------------------------------------------------------------------------------

Road控制器

public class Road {

private List vechicles = new ArrayList();

private String name =null;

public Road(String name){

this.name = name;

//模拟车辆不断随机上路的过程

ExecutorService pool = Executors.newSingleThreadExecutor();

pool.execute(new Runnable(){

public void run(){

for(int i=1;i<1000;i++){

try {

Thread.sleep((new Random().nextInt(10) + 1) * 1000);

} catch (InterruptedException e) {

e.printStackTrace();

}

vechicles.add(Road.this.name + "_" + i);//访问外部类不用finally

}

}

});

//每隔一秒检查对应的灯是否为绿，是则放行一辆车

ScheduledExecutorService timer =  Executors.newScheduledThreadPool(1);

timer.scheduleAtFixedRate(

new Runnable(){

public void run(){

if(vechicles.size()>0){

boolean lighted = Lamp.valueOf(Road.this.name).isLighted();

if(lighted){

System.out.println(vechicles.remove(0) + " is traversing !");

}

}

}

},

1,

1,

TimeUnit.SECONDS);

}

}