如何将创建的对象存储到ArrayList中并将其返回？

时间：2014-03-10 02:05:40

标签： java object arraylist abstract-class extends

我被要求创建一个名为listOfWorkers的方法，在其中我将通过从文件“workers.txt”读取数据来创建我拥有的每个类型的3个工作者的对象，然后将对象存储到类型的ArrayList中工人并将其归还。我已经设法通过从文件中读取数据来制作3类工作者的每种类型的对象，但现在我不知道如何将它们存储到ArrayList中。有帮助吗？

我正在编写课程

import java.util.*;
import java.io.*;

public class WorkerBenefits 
{
public ArrayList<Worker> listOfWorkers()
{



    try
    {

        File ifile = new File("worker.txt");
        Scanner scan = new Scanner(ifile);
        while (scan.hasNextLine())
        {
            String line = scan.nextLine();
            StringTokenizer st = new StringTokenizer(line,",");
            String jobs = st.nextToken();
            Jobs jobType = Jobs.valueOf(jobs);
            //Engineer Object type 
            if (jobType == Jobs.ELECTRICAL_ENGINEER || jobType == Jobs.MECHANICAL_ENGINEER)
            {
                String name = st.nextToken();
                String str1 = st.nextToken();
                int social = Integer.parseInt(str1);
                String str2 = st.nextToken();
                int years = Integer.parseInt(str2);
                String str3 = st.nextToken();
                double weeklyBen = Double.parseDouble(str3);
                Engineer eng = new Engineer(name,social,years,jobType,weeklyBen);
            }
            //Admin. Person. Object  type
            else if (jobType == Jobs.ADMINISTRATIVE_SECRETARY || jobType == Jobs.ADMINISTRATIVE_ASSISTANT)
            {
                String name = st.nextToken();
                String str1 = st.nextToken();
                int social = Integer.parseInt(str1);
                String str2 = st.nextToken();
                int years = Integer.parseInt(str2);
                String str3 = st.nextToken();
                double rate = Double.parseDouble(str3);
                String str4 = st.nextToken();
                double hours = Double.parseDouble(str4);
                AdministrativePersonnel ap = new AdministrativePersonnel(name,social,years,jobType,rate,hours);
            }
            //Management Object type
            else if (jobType == Jobs.ENGINEERING_MANAGER || jobType == Jobs.ADMINISTRATIVE_MANAGER)
            {
                String name = st.nextToken();
                String str1 = st.nextToken();
                int social = Integer.parseInt(str1);
                String str2 = st.nextToken();
                int years = Integer.parseInt(str2);
                String str3 = st.nextToken();
                double weeklyBen = Double.parseDouble(str3);
                String str4 = st.nextToken();
                double bonus = Double.parseDouble(str4);
                Management mang = new Management(name,social,years,jobType,weeklyBen,bonus);
            }
        }
    }
    catch (IOException ioe)
    {
        System.out.println("Something went wrong");
    }
    return ArrayList;
}

}

以下是其他类的代码，以防你们需要它们：

工作

public enum Jobs {ELECTRICAL_ENGINEER, MECHANICAL_ENGINEER, ADMINISTRATIVE_SECRETARY, ADMINISTRATIVE_ASSISTANT, ENGINEERING_MANAGER, ADMINISTRATIVE_MANAGER, NONE};

工人

public abstract class Worker
{
public String name;
public int socialSecurity;
private int yearsExperience;
public Jobs et = null;
public static int id = 0;
public int currentID = 0;

public Worker ()
{
    name = "AnyName";
    socialSecurity = 12345;
    yearsExperience = 0;
    et = Jobs.NONE;
    id++;
    currentID = id;
}

public Worker (String n, int ss, int ye, Jobs j)
{
    id++;
    currentID = id;
    name = n;
    socialSecurity = ss;
    yearsExperience = ye;
    et = j;
}

public String getName()
{
    return name;
}

public int getSocialSecurity()
{
    return socialSecurity;
}

public int getYearsExperience()
{
    return yearsExperience;
}

public Jobs getJobs()
{
    return et;
}

public void setName(String n1)
{
    name = n1;
}

public void setSocialSecurity(int ss1)
{
    socialSecurity = ss1;
}

public void setYearsExperience(int ye1)
{
    yearsExperience = ye1;
}

public void setJobs(Jobs et1)
{
    et = et1;
}

public abstract double benefitsCalculation(Jobs et2);

public String toString()
{
    String output = "The name is: " + name + "The Job type is: " + et + "The id    is: " + currentID;
    return output;
}
}

工程师

public class Engineer extends Worker
{
private double weeklyBenefits;

public Engineer ()
{
    super();
    weeklyBenefits = 400.00;
}

public Engineer (String n, int ss, int ye, Jobs j, double wb)
{
    super(n,ss,ye,j);
    weeklyBenefits = wb;
    super.setName(n);
    super.setSocialSecurity(ss);
    super.setYearsExperience(ye);
    super.setJobs(j);

}


public double benefitsCalculation(Jobs et2)
{
    double benefits = 0.0;
    if (et2 == Jobs.ELECTRICAL_ENGINEER)
    {
        benefits = weeklyBenefits+super.getYearsExperience()*120.00;
    }
    else if (et2 == Jobs.MECHANICAL_ENGINEER)
    {
        benefits = weeklyBenefits/2+super.getYearsExperience()*120.00;
    }
    else if (et2 != Jobs.ELECTRICAL_ENGINEER || et2 != Jobs.MECHANICAL_ENGINEER)
    {
        benefits = 0;
    }
    return benefits;
}

public double getWeeklyBenefits()
{
    return weeklyBenefits;
}

public void setWeeklyBenefits(double wb)
{
    weeklyBenefits = wb;
}

public String toString()
{
    String output = "The benefit is " + weeklyBenefits + super.toString();
    return output;
}
}

行政人员

public class AdministrativePersonnel extends Worker
{
private double rate;
private double hours;

    public AdministrativePersonnel()
    {
        super();
        rate = 10.0;
        hours = 10.0;
    }

    public AdministrativePersonnel(String n, int ss, int ye, Jobs j, double r, double h)
    {
        super(n,ss,ye,j);
        rate = r;
        hours = h;
        super.setName(n);
        super.setSocialSecurity(ss);
        super.setYearsExperience(ye);
        super.setJobs(j);
    }

    public double benefitsCalculation (Jobs et2)
    {
        double benefits = 0.0;
        if (et2 == Jobs.ADMINISTRATIVE_SECRETARY)
        {
            benefits = rate*hours+super.getYearsExperience()*15.00; 
        }
        else if(et2 == Jobs.ADMINISTRATIVE_ASSISTANT)
        {
            benefits = rate*hours+super.getYearsExperience()*25.00;
        }
        else if (et2 != Jobs.ADMINISTRATIVE_SECRETARY || et2 != Jobs.ADMINISTRATIVE_ASSISTANT)
        {
            benefits = 0;
        }
        return benefits;
    }

    public double getRate()
    {
        return rate;
    }

    public double getHours()
    {
        return hours;
    }

    public void setRate(double r1)
    {
        rate = r1;
    }

    public void setHours(double h1)
    {
        hours = h1;
    }

    public String toString()
    {
        String output = "The rate is: " + rate + "The hours are: " + hours +  super.toString();
        return output;
    }
}

管理

public class Management extends Worker
{
private double weeklyBenefits;
private double bonus;

public Management()
{
    super();
    weeklyBenefits = 0.0;
    bonus = 0.0;
}

public Management(String n, int ss, int ye, Jobs j, double wb, double b)
{
    super(n,ss,ye,j);
    weeklyBenefits = wb;
    bonus = b;
    super.setName(n);
    super.setSocialSecurity(ss);
    super.setYearsExperience(ye);
    super.setJobs(j);
}

public double benefitsCalculation (Jobs et2)
{
        double benefits = 0.0;
        if (et2 == Jobs.ENGINEERING_MANAGER)
        {
            benefits = weeklyBenefits+bonus;    
        }
        else if(et2 == Jobs.ADMINISTRATIVE_MANAGER)
        {
            benefits = weeklyBenefits+0.5*bonus;
        }
        else if (et2 != Jobs.ENGINEERING_MANAGER || et2 != Jobs.ADMINISTRATIVE_MANAGER)
        {
            benefits = 0;
        }
        return benefits;
}

public double getWeeklyBenefits()
{
    return weeklyBenefits;
}

public double getBonus()
{
    return bonus;
}

public void setWeeklyBenefits(double wb)
{
    weeklyBenefits = wb;
}

public void setBonus(double b)
{
    bonus = b;
}

public String toString()
{
    String output = "The weekly benefits are: " + weeklyBenefits + "The bonus is: " + bonus + super.toString();
    return output;
}
}

3 个答案:

答案 0 :(得分：1)

listOfWorkers()方法需要创建一个worker列表，添加每个新的worker对象然后返回列表。

public List<Worker> listOfWorkers()
{
  List<Worker> workers = new ArrayList<Worker>();

    try
    {

        File ifile = new File("worker.txt");
        Scanner scan = new Scanner(ifile);
        while (scan.hasNextLine())
        {
            String line = scan.nextLine();
            StringTokenizer st = new StringTokenizer(line,",");
            String jobs = st.nextToken();
            Jobs jobType = Jobs.valueOf(jobs);
            //Engineer Object type 
            if (jobType == Jobs.ELECTRICAL_ENGINEER || jobType == Jobs.MECHANICAL_ENGINEER)
            {
                String name = st.nextToken();
                String str1 = st.nextToken();
                int social = Integer.parseInt(str1);
                String str2 = st.nextToken();
                int years = Integer.parseInt(str2);
                String str3 = st.nextToken();
                double weeklyBen = Double.parseDouble(str3);
                Engineer eng = new Engineer(name,social,years,jobType,weeklyBen);
                workers.add(eng);
            }
            //Admin. Person. Object  type
            else if (jobType == Jobs.ADMINISTRATIVE_SECRETARY || jobType == Jobs.ADMINISTRATIVE_ASSISTANT)
            {
                String name = st.nextToken();
                String str1 = st.nextToken();
                int social = Integer.parseInt(str1);
                String str2 = st.nextToken();
                int years = Integer.parseInt(str2);
                String str3 = st.nextToken();
                double rate = Double.parseDouble(str3);
                String str4 = st.nextToken();
                double hours = Double.parseDouble(str4);
                AdministrativePersonnel ap = new AdministrativePersonnel(name,social,years,jobType,rate,hours);
                workers.add(ap);
            }
            //Management Object type
            else if (jobType == Jobs.ENGINEERING_MANAGER || jobType == Jobs.ADMINISTRATIVE_MANAGER)
            {
                String name = st.nextToken();
                String str1 = st.nextToken();
                int social = Integer.parseInt(str1);
                String str2 = st.nextToken();
                int years = Integer.parseInt(str2);
                String str3 = st.nextToken();
                double weeklyBen = Double.parseDouble(str3);
                String str4 = st.nextToken();
                double bonus = Double.parseDouble(str4);
                Management mang = new Management(name,social,years,jobType,weeklyBen,bonus);
                workers.add(mang);
            }
        }
    }
    catch (IOException ioe)
    {
        System.out.println("Something went wrong");
    }
    return workers;
}

答案 1 :(得分：1)

public ArrayList<Worker> listOfWorkers()
{


    List<Worker> list=new ArrayList<Worker>();

    try
    {

        File ifile = new File("worker.txt");
        Scanner scan = new Scanner(ifile);
        while (scan.hasNextLine())
        {
             // no change
            if (jobType == Jobs.ELECTRICAL_ENGINEER || jobType == Jobs.MECHANICAL_ENGINEER)
            {
               // no change
                Worker eng = new Engineer(name,social,years,jobType,weeklyBen);
                list.add(eng);
            }
            else if()
            {
              //do same as above for other workers
            }
        }
        return list;
}

答案 2 :(得分：1)

在try块之前，创建一个新的worker对象ArrayList：

ArrayList<Worker> workerList = new ArrayList<Worker>();

在while循环的开头，声明一个新的worker变量但是还没有创建它：

Worker worker = null;

在每个if块中，将结果分配给worker，而不是将其分配给Engineer，Management或AdministrativePersonnel类型的新变量。例如，替换为：

Engineer eng = new Engineer(name,social,years,jobType,weeklyBen);

用这个：

worker = new Engineer(name,social,years,jobType,weeklyBen);

这是合法的，因为Engineer，Management和AdministrativePersonnel都是Worker的子类。

在while循环结束之前，将新工作人员添加到列表中：

workerList.add(worker);

最后，从函数返回workerList。

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