用JAVA实现先到先服务和短作业优先算法

1、首先先写一个实体类来表示进程

package demo;

public class Progress {
	//到达时间
	public int arriveTime;
	//运行时间
	public int runTime;
	//完成时间
	public int finishTime;
	//周转时间
	public int totalTime;
	//带权周转时间
	public float weightTotalTime;
	//进程名
	public String name;
	
	
	public Progress(String name,int arriveTime,int runTime){
		this.name = name;
		this.arriveTime = arriveTime;
		this.runTime = runTime;
	}
	
	//获得周转时间
	public void getTotalTime(){
		
		totalTime = finishTime - arriveTime;
	}
	//获得带权周转时间
	public void getWeightTotalTime(){
		weightTotalTime = (float)totalTime/runTime;
	}
	
	//打印结果
	@Override
	public String toString() {
		return name+"到达时间："+arriveTime+"运行时间："+runTime+"完成时间："+finishTime+"周转时间："+totalTime+"带权周转时间："+weightTotalTime;
	}
}

2、将需要处理的进程存放到progressList中

package demo;

import java.util.ArrayList;

public class ProgressList {

	//存放进程
	private static ArrayList<Progress> progressList;

	public ArrayList<Progress> getProgressList() {
		return progressList;
	}
	
	//将四个进程存放到progressList中
	static {
		progressList  = new ArrayList<Progress>();
		progressList.add(new Progress("P1",0,3));
		progressList.add(new Progress("P2",1,5));
		progressList.add(new Progress("P3",2,2));
		progressList.add(new Progress("P4",3,3));
	}
}

3、实现两个算法

package demo;

import java.util.ArrayList;

public class Service {
	
	
	private ArrayList<Progress> progressList;
	
	//初始化进程
	public void init() {
		progressList = new ProgressList().getProgressList();
		for(Progress p:progressList) {
			p.finishTime = 0;
			p.totalTime = 0;
			p.weightTotalTime = 0;
		}
	}
	
	//先到先服务
	public ArrayList<Progress> FCFS() {
		int time = 0;
		for(int i=0;i<progressList.size();i++) {
			int flag = progressList.size();
			int compare = 100;
			for(Progress p:progressList) {
				if(p.finishTime==0) {
					if(p.arriveTime<compare) {
						compare = p.arriveTime;
						flag = progressList.indexOf(p);
					}
				}
			}
			
			//更新进程
			progressList.get(flag).finishTime = time + progressList.get(flag).runTime;
			progressList.get(flag).getTotalTime();
			progressList.get(flag).getWeightTotalTime();
			//更新时间
			time = progressList.get(flag).finishTime;
		}
		return progressList;
	}
	
	//短作业优先
	public ArrayList<Progress> SJF(){
		int time = 0;
		for(int i=0;i<progressList.size();i++) {
			int flag = progressList.size();
			int compare = 100;
			for(Progress p:progressList) {
				//判断此时该进程是否到达
				if(p.arriveTime<=time) {
					//判断该进程是否已完成
					if(p.finishTime==0) {
						//判断该进程运行时间是否最短
						if(p.runTime<compare) {
							compare = p.runTime;
							flag = progressList.indexOf(p);
						}
					}
				}
			}
			
			//更新进程
			progressList.get(flag).finishTime = time + progressList.get(flag).runTime;
			progressList.get(flag).getTotalTime();
			progressList.get(flag).getWeightTotalTime();
			
			//更新时间
			time = progressList.get(flag).finishTime;
		}
		return progressList;
	}
}

4、主方法

package demo;

import java.util.ArrayList;

public class CPU {
	public static void main(String[] args) {
		Service service = new Service();
		
		//先到先服务
		service.init();
		ArrayList<Progress> list = service.FCFS();
		System.out.println("先到先服务的执行过程：");
		for(Progress p:list) {
			System.out.println(p);
		}
		
		//短作业优先
		service.init();
		list = service.SJF();
		System.out.println("短作业优先的执行过程：");
		for(Progress p:list) {
			System.out.println(p);
		}
	}
}

程序截图

程序有些不完善的地方、欢迎修改