Java 如何通过获取更改的方法运行更改对象的整个arrayList

好的，所以我正在研究的程序需要创建一个至少1000个变更对象的arrayList，然后计算由该数量产生的变更，就像在销售点环境中一样。我所有的东西都在工作，除了我被如何计算变化的问题难倒了。我在另一个类中编写了一些方法来实现这一点，但我不知道如何将整个arrayList传递给它们来实现这一点。如果有人能帮我这个忙，我将不胜感激

更改类别：

public class Change {

private double amount, remainingAmount;
private int occurences;


public Change() {
    super();
    this.amount = 17.87;
    this.remainingAmount = (int)(amount * 100);
}

public Change(double amount, double remainingAmount) {
    super();
    this.amount = amount;
    this.remainingAmount = remainingAmount;
}

public Change(float nextChange) {
    this.amount = amount;
    this.remainingAmount = remainingAmount;
}

public double getAmount() {
    return amount;
}

public void setAmount(double amount) {
    this.amount = amount;
}

public double getRemainingAmount() {
    return remainingAmount;
}
public void incrementOccurence()  {
    occurences++;
}

public void setRemainingAmount(double remainingAmount) {
    this.remainingAmount = remainingAmount;
}
public double numberOfOneDollars() {
    int numberOfOneDollars = (int) (remainingAmount / 100);
    remainingAmount = remainingAmount % 100;
    return numberOfOneDollars;
}

public double numberOfQuarters() {
    int numberOfQuarters = (int) (remainingAmount / 25);
    remainingAmount = remainingAmount % 25;
    return numberOfQuarters;
}
public double numberOfDimes() {
    int numberOfDimes = (int) (remainingAmount / 10);
    remainingAmount = remainingAmount % 10;
    return numberOfDimes;
}
public double numberOfNickels() {
    int numberOfNickels = (int) (remainingAmount / 5);
    remainingAmount = remainingAmount % 5;
    return numberOfNickels;
}
public int numberOfPennies() {
    int numberOfPennies = (int) remainingAmount;
    return numberOfPennies;
}

@Override
public String toString() {
    return "Change [amount=" + amount + ", remainingAmount="
            + remainingAmount + "]\n";
}
}

更改ArrayList类：

import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.Scanner;
public class ChangeArrayList {
private ArrayList<Change> changeArray = new ArrayList<Change>();
private static int numOfChangeObjects = 1000;
private static String FILE_NAME = "changeData.dat";

public static void makeChangeData() {

    PrintWriter outputStream = null;
    try
    {
        outputStream = new PrintWriter(FILE_NAME);
    }
    catch(FileNotFoundException e)  {
        System.out.println("Error opening the file " + FILE_NAME);
        System.exit(0);
    }

    for (int count = 0; count < numOfChangeObjects; count++) {
        //get random number between 0-1, move decimal right two places, typecast to float
        //to get rid of decimals, then divide by 10.0 to get decimal left one place
        //then add 3 to make sure numbers are >3 
        DecimalFormat df = new DecimalFormat("#.##");
        double changeData = (float)(Math.random() * 100)/10.0 + 3;
        double twoDecimal = Double.valueOf(df.format(changeData));
        outputStream.println(twoDecimal + " ");
    }
    outputStream.close();
    System.out.println("Those lines were written to " + FILE_NAME);
}

public void makeChangeArray(String fileName)  {

    changeArray = new ArrayList<Change>();

    Scanner inputStream = null;
    try
    {
        inputStream = new Scanner(new File(FILE_NAME));
    }
    catch(FileNotFoundException e)
    {
        System.out.println("Error opening the file " + 
                FILE_NAME);
        System.exit(0);
    }

    while (inputStream.hasNext())
    {
        //read in a change object from the file
        float nextChange = inputStream.nextFloat();

        //Stuck here. Can't figure out what to put in to make this work
        //everything else works except this. My change keeps coming out as 0
        changeArray.add(new Change(nextChange));
        //Stuck here. Can't figure out what to put in to make this work
        //everything else works except this. My change keeps coming out as 0
    }
    inputStream.close();
}

public void writeToFile()  {
    String fileName = "out.txt"; //The name could be read from 
    //the keyboard.
    PrintWriter outputStream = null;
    try
    {
        outputStream = new PrintWriter(fileName);
    }
    catch(FileNotFoundException e)
    {
        System.out.println("Error opening the file " + 
                fileName);
        System.exit(0);
    }

    outputStream.println(toString());

    outputStream.close( );
    System.out.println("Those lines were written to " + 
            fileName);
}

public String toString() {
    String s = "";

    for (int i = 0; i < changeArray.size(); i++) {
        s += changeArray.get(i).toString(); }
    return s;
}

public static void main(String[] args) {

    ChangeArrayList.makeChangeData();

    ChangeArrayList tester = new ChangeArrayList();

    tester.makeChangeArray("changeData.dat");

    //Something should go here to calculate change
    //Not sure how to go about doing this

    tester.writeToFile();
}
}

导入java.io.File；
导入java.io.FileNotFoundException；
导入java.io.PrintWriter；
导入java.text.DecimalFormat；
导入java.util.ArrayList；
导入java.util.Scanner；
公共类变更列表{
私有ArrayList changeArray=新ArrayList（）；
私有静态int numOfChangeObjects=1000；
私有静态字符串文件\u NAME=“changeData.dat”；
公共静态void makeChangeData（）{
PrintWriter outputStream=null；
尝试
{
outputStream=新的PrintWriter（文件名）；
}
catch（filenotfounde异常）{
System.out.println（“打开文件时出错”+文件名）；
系统出口（0）；
}
对于（int count=0；count

方法1:

您可以在

ChangeArrayList

中为

changeArray

创建getter方法。在main方法中调用

makeChangeArray（）

方法后，可以调用getter方法并将返回的arraylist作为参数传递给所需的方法

---

方法2:我更喜欢这种方法

不要声明类级别的changeArray，而是在

makeChangeArray（）

方法中声明它，并将返回类型更改为

List

而不是

void

，然后返回准备好的arraylist