高薪面试题01—交通灯管理系统

 

 

 

package com.isoftstone.iterview.traffic;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

public class Road {
	List<String> vechicles = new ArrayList<String>();
	
	private String name = null;
	public Road(String name){
		this.name = name;
		
		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)*10);
					} catch (InterruptedException e) {
						
						e.printStackTrace();
					}
					vechicles.add(Road.this.name + ":" + i);
				}
			}
		});
		
		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);
	
	}
}

 

package com.isoftstone.iterview.traffic;

public enum Lamp {
	S2N("N2S","S2W",false),S2W("N2E","E2W",false),E2W("W2N","E2S",false),E2S("S2N","W2N",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 Lamp(){
		
	}
	private boolean lighted;
	private String opposite;
	private String next;
	
	public boolean isLighted(){
		return lighted;
	}
	
	public void ligth(){
		this.lighted = true;
		if(opposite != null){
			Lamp.valueOf(opposite).ligth();
		}
		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.ligth();
		}
		return nextLamp;
	}
}

 

package com.isoftstone.iterview.traffic;

import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

public class LampController {
	private Lamp currentLamp;
	
	public LampController(){
		currentLamp = Lamp.S2N;
		currentLamp.ligth();
		
		ScheduledExecutorService timer = Executors.newScheduledThreadPool(1);
		timer.scheduleAtFixedRate(
				new Runnable(){
					public void run(){
						currentLamp = currentLamp.blackOut();
					}
				}, 
				10, 
				10, 
				TimeUnit.SECONDS);
	}
}

 

package com.isoftstone.iterview.traffic;
/*S2N,S2W,E2W,E2S,N2S,N2E,W2E,W2N,S2E,E2N,N2W,W2S;*/
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<directions.length; i++){
			new Road(directions[i]);
		}
		
		new LampController();
	}

}