在Java中对对象的数组列表进行排序 [英] Sort an arraylist of objects in java

问题描述

我正在创建一些不同的CPU调度算法的模拟，并且还想同时学习一种新语言.我遇到的麻烦是试图根据进程的到达时间对进程的数组列表进行排序.我遇到的错误是没有为Collections.sort(processes)找到合适的方法，而且我不太确定该怎么做.

I'm working on creating a simulating of some different CPU scheduling algorithms and also wanted to learn a new language at the same time. The trouble I'm running into is trying to sort an arraylist of processes based on their arrival time. The error I'm running into is that there is no suitable method found for Collections.sort(processes), and I'm not really sure what to do.

Process.java

Process.java

import java.util.Random;
public class Process implements Comparable
{

    private Random generator;
    private String name;
    private int burstTime;
    private int priority;
    private int arrivalTime;

    /**
     * Process constructor where the user choose the values
     * @param nameValue name of the process
     * @param burstTimeValue burst time of the process
     * @param priorityValue priority of the process
     * @param arrivalTimeValue arrival time of the process
     */
    public Process(String nameValue, int burstTimeValue, int priorityValue,
            int arrivalTimeValue)
    {
        name = nameValue;
        burstTime = burstTimeValue;
        priority = priorityValue;
        arrivalTime = arrivalTimeValue;
    }

    /**
     * Process constructor that randomizes the values of
     * name, burst time, priority, and arrival time.
     */
    public Process()
    {
        generator = new Random();
        name = "Process" + generator.nextInt(10000);
        burstTime = generator.nextInt(10);
        priority = generator.nextInt(5);
        arrivalTime = generator.nextInt(30);
    }

    /**
     * Returns the name of the process
     * @return name the name of the process
     */
    public String getName()
    {
        return name;
    }

    /**
     * Sets the name of the process
     * @param aValue value to set the process name to
     */
    public void setName(String aValue)
    {
        name = aValue;
    }

    /**
     * Returns the burst time of the process
     * @return burstTime the burst time of the process
     */
    public int getBurstTime()
    {
        return burstTime;
    }

    /**
     * Sets the burst time of a process
     * @param aValue the value for the burst time of a process
     */
    public void setBurstTime(int aValue)
    {
        burstTime = aValue;
    }

    /**
     * Returns the priority value of the process
     * @return priority the priority of the process
     */
    public int getPriority()
    {
        return priority;
    }

    /**
     * Sets the priority of a process
     * @param aValue value for priority
     */
    public void setPriority(int aValue)
    {
        priority = aValue;
    }

    /**
     * Returns the arrival time of the process
     * @return arrival time the arrival time of the process
     */
    public int getArrivalTime()
    {
        return arrivalTime;
    }

    /**
     * Sets the arrival time value
     * @param aValue value for arrival time
     */
    public void setArrivalTime(int aValue)
    {
        arrivalTime = aValue;
    }

    /**
     * Overrides the toString method from the String class
     * Returns a printout of the object's variables
     * @return printout of the object's variables
     */
    @Override
    public String toString()
    {
        return "Process[name=" + name + " bTime=" + burstTime
                + " priority=" + priority + " aTime=" + arrivalTime +"]";
    }

    /**
     * Compares two process objects
     * @param otherObject another process object
     * @return the order of two processes
     */
    @Override
    public int compareTo(Object otherObject)
    {
        Process other = (Process) otherObject;
        if (arrivalTime < other.arrivalTime) return -1;
        if (arrivalTime == other.arrivalTime) return 0;
        return 1;
    } 
}

Comparable.java

Comparable.java

public interface Comparable
{
    int compareTo(Object otherObject);
}

Cpu.java

import java.util.ArrayList;
import java.util.Collections;
public class Cpu implements
{
    private ArrayList<Process> processes;

    /**
     * 
     */
    public Cpu()
    {
        processes = new ArrayList<Process>();
    }

    /**
     * Adds a process to the ArrayList
     * @param p the process that is being added
     */
    public void addProcess(Process p)
    {
        processes.add(p);
    }

    public void sort()
    {
        Collections.sort(processes);
    }      
}

推荐答案

您需要实现

You need to implement java.lang.Comparable. Writing your own won't work, because it's in another package.

因此，只需为您的Process类添加import声明，然后删除您自己制作的Comparable接口. (+请参阅第一个评论)

So just add the import declaration in for your Process class and delete your self made Comparable interface. (+ see first comment)

这篇关于在Java中对对象的数组列表进行排序的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！