如何使方法添加到arraylist

Question

我怎么办 make 一个名为 withdraw 的方法，从账户中提取指定的金额，然后添加事务到事务的ArrayList。  一个名为 deposit 的方法，将指定的金额存入帐户，然后添加交易到交易的ArrayList。

package hw1josezaragoza;

import java.util.Date;
import java.util.ArrayList;

/**
 *
 * @author jose
 */
public class Hw1josezaragoza {

/**
 * @param args the command line arguments
 */
public static void main(String[] args) {
    // TODO code application logic here

    Account acc = new Account(1122, "George", 1000);
    acc.deposit(3000);
    acc.withdraw(2500);
    acc.setInterestRate(1.5);
    acc.getMonthlyInterestRate();


    System.out.print("The account holder's name: " + acc.getName()
            + ".\nThe annual interest rate: " + acc.getInterestRate()
            + ".\nThe balance: " + acc.getBalance() 
            + ".\nThe monthly interest: " + acc.getMonthlyInterest() 
            + "\nAccount created on " + acc.getDate());


        }
 }

交易Class:

class Transaction {

    private Date dateOfTrans;
private char typeOfTrans;
char WithDraw = 'W';
char Deposit = 'D';
private double amount;
private double balance;
private String description;

public Transaction(char Type, double newAmount, double newBalance, String newDescription, Date date) {
    typeOfTrans = Type;
    amount = newAmount;
    balance = newBalance;
    description = newDescription;
    dateOfTrans = date;
}

public Date getDate() {
    return dateOfTrans;
}

public char getType() {
    return typeOfTrans;
}

public double getAmount() {
    return amount;
}

public String getDescription() {
    return description;
}

public double getBalance() {
    return balance;
    }
}

帐号Class:

class Account {

    private int Id = 0;
private String name;
private double balance = 0;
private double annualRate = 0.0;

private Date dateCreated = new Date();
private ArrayList Transaction = new ArrayList();

Account() {
    Id = 0;
    balance = 0.0;
    annualRate = 0.0;
}

Account(int newId, double newBalance) {
    Id = newId;
    balance = newBalance;
}

Account(int newId, String newName, double newBalance) {
    Id = newId;
    name = newName;
    balance = newBalance;
}

public int getId() {
    return Id;
}

public void setId(int newId) {
    Id = newId;
}

public double getBalance() {
    return balance;
}

public void setBalance(double newBalance) {
    balance = newBalance;
}

public String getName() {
    return name;
}

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

public double getInterestRate() {

    return annualRate;
}

public void setInterestRate(double annualRate) {

    this.annualRate = annualRate/100;
}

public Date getDate() {
    return dateCreated;
}

public void setDate(Date newDate) {
    dateCreated = newDate;
}

double monthlyInterestRate;
double monthlyInterest;

public double getMonthlyInterestRate( ) {
    monthlyInterestRate = annualRate / 12;
    return monthlyInterestRate;
}

public double getMonthlyInterest() {
    monthlyInterest =balance * monthlyInterestRate;
    return monthlyInterest;
}

double withdraw(double amount) {
    balance -= amount;
    return balance;
}

double deposit(double amount) {
    balance += amount;

    return balance;


  }

}

Answer 1

首先，您不能将数组列表命名为与类相同的名称。假设你把arraylist的名字改成transaction，在withdraw方法的末尾插入下面的代码。

transaction.add(new Transaction("W", amount, balance, "Withdrawal", new Date()));

并将此放入存款方式。

transaction.add(new Transaction("D", amount, balance, "Deposit", new Date()));

此外，建议将 arraylist 声明语句更改为以下内容：

private ArrayList<Transaction> transaction = new ArrayList<Transaction>();

如何使方法添加到arraylist

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