在我的程序中，用户输入值并将其存储在arrayList中。 ArryList对象被写入文件。我已经使用file-i / o，object-i / o stream进行写入和readin in file.Now我想在对象之间执行加法和减法（int or double）。即从一个帐户中提取资金应该与另一个帐户一起添加，并且必须减去它们的值并将其与特定帐户的金额相加。最后，我希望必须更新该值，以便打印出来并显示当前状态。我怎么能这样做？
这是主要课程：
public class BankApp_Assignment {
//static int numOfAcc = 0;
public static void main(String[] args) {
System.out.println("WELCOME TO OUR BANK!\n\n");
List<BankAccount> bankAccounts = new ArrayList<BankAccount>();
List<BankAccount> bankAccounts2 = new ArrayList<BankAccount>();
ReaderWriter rw=new ReaderWriter();
while (true) {
System.out.println("Choose your option:\n"
+ "1. Create new account\n"
+ "2. Deposit/withdraw\n"
+ "3. View One account\n"
+ "4. Deleting an account\n"
+ "5. View all the accounts\n"
+ "6. Return to menu\n");
System.out.println("*************\n"
+ "************");
option1 = sc.nextInt();
sc.nextLine();
//switch-case starts
switch (option1) {
case 1:
//create account
BankAccount bankAcc = new BankAccount();
System.out.println("Enter Full Name:");
bankAcc.setName(sc.nextLine());
System.out.println("Choose an Account Number:");
bankAcc.setAccNum(sc.nextInt());
System.out.println("Choose the initial amount:");
bankAcc.setInitiateAmount(sc.nextDouble());
//adding those into the arrayList
bankAccounts.add(bankAcc);
rw.writeToFile(bankAccounts);
System.out.println("-------------\n"
+ "-------------");
break;
case 2:
bankAccounts2=(List<BankAccount>)rw.readFromFile();
//First displaying the current accouns info
System.out.println("Name \tAccount No \tInitial Amount");
for (BankAccount bankAccount : bankAccounts2) {
System.out.println(bankAccount);
}
System.out.println("\t\t.........\n"
+ "\t\t.........");
System.out.println("To transfer money within the bank accounts enter 1\n"
+ "To deposit/withdraw money in the same account enter 2");
option2 = sc.nextInt();
sc.nextLine();
//inner switch-case starts
switch (option2) {
case 1:
/*
BankAccount is the class for setter and getter
bankAccounts2 is the arrayList for reading objects from file
*/
bankAccounts2 = (List<BankAccount>) rw.readFromFile();
BankAccount fromAcc = null;
BankAccount toAcc = null;
System.out.println("Enter the account number you want to withdraw from:");
withdraw_accNum = sc.nextInt();
System.out.println("Enter the amount you want to withdraw:");
withdraw_amount = sc.nextDouble();
System.out.println("Enter the account number you want to deposit to:");
deposit_accNum = sc.nextInt();//the deposit amount is alwyas the same as withdraw_amount
//find the matching acc number:withdraw_accNum
for (BankAccount listItemsFirst : bankAccounts2) {
//if the withdraw acc num matches with the given one
if (listItemsFirst.getAccNum() == withdraw_accNum) {
//store it
fromAcc = listItemsFirst;
break;
}
}
//find the matching acc number: deposit_accNum
for (BankAccount listItemsSec : bankAccounts2) {
//if the withdraw acc num matches with the given one
if (listItemsSec.getAccNum() == deposit_accNum) {
//store it
toAcc = listItemsSec;
break;
}
}
//if the withdraw amount is bigger than the current balance
if (withdraw_amount > fromAcc.getInitialAmount()) {
System.out.println("Withdrawing Amount was bigger than the Initial amount.\nChoose the menu again. .");
break;
}
//subtracting and adding the withdrawn amount
fromAcc.setInitiateAmount(fromAcc.getInitialAmount() - withdraw_amount);
toAcc.setInitiateAmount(toAcc.getInitialAmount() + withdraw_amount);
System.out.println("DONE!\t print them out to see the current status.");
System.out.println("");
break;
case 2://deposit/withdraw money in the same accounts
bankAccounts2=(List<BankAccount>)rw.readFromFile();
BankAccount fromAcc_SameAcc = null;
BankAccount toAcc_SameAcc = null;
System.out.println("Enter the account number you want to deposit or withdraw from:");
//read the accNum
depOrWithAccountNum = sc.nextInt();
System.out.println("Enter the amount (To withdraw enter a negative value)");
//read the amount
depOrWithAmount = sc.nextDouble();
//checking the matching account number in arrayList
for (BankAccount listItemsThird : bankAccounts2) {
if (listItemsThird.getAccNum() == depOrWithAccountNum) {
fromAcc_SameAcc = listItemsThird;
break;
}
}
if (depOrWithAmount - 1 < fromAcc_SameAcc.getInitialAmount()) {
System.out.println("Withdraw amount is bigger than the current amount.\nChoose the menu again. .");
break;
}
if (depOrWithAmount < 0) {//the amount is negative
fromAcc_SameAcc.setInitiateAmount(fromAcc_SameAcc.getInitialAmount() + depOrWithAmount);
} else {
fromAcc_SameAcc.setInitiateAmount(fromAcc_SameAcc.getInitialAmount() + depOrWithAmount);
}
break;
}
//inner switch-case ends
System.out.println("\n\n");
break;
case 3:
//View One account
bankAccounts2=(List<BankAccount>)rw.readFromFile();
BankAccount viewOneAccountNum = null;
System.out.println("Enter the account number you want to see:");
viewOneAcc = sc.nextInt();
System.out.println("Name\tAccount No\tInitial Amount");
for (BankAccount viewOneAccountProperty : bankAccounts2) {
if (viewOneAccountProperty.getAccNum() == viewOneAcc) {
//viewOneAccountNum=viewOneAccountProperty;
viewOneAccountNum = viewOneAccountProperty;
System.out.println(viewOneAccountNum);
}
System.out.println("");
}
break;
case 4:
bankAccounts2=(List<BankAccount>)rw.readFromFile();
//BankAccount AccToDel = null;
//Deleting an account
Iterator<BankAccount> it = bankAccounts2.iterator();
System.out.println("Enter the account you want to delete:");
deleteAcc = sc.nextInt();
while (it.hasNext()) {
BankAccount next = it.next();
if (next.getAccNum() == deleteAcc) {
it.remove();
}
}
rw.writeToFile(bankAccounts2);
break;
case 5:
//View all the accounts/printing them out
bankAccounts2=(List<BankAccount>)rw.readFromFile();
System.out.println("Name\tAccount No\tInitial Amount");
for (BankAccount bankAccount : bankAccounts2) {
System.out.println(bankAccount);
}
System.out.println("\n\n");
break;
case 6:
//Quit
return;
}
//switch-case ends
}
}
}
读写器：
public class ReaderWriter{
public void writeToFile(List<BankAccount> accounts){
try {
FileOutputStream fos=new FileOutputStream("C:\\Users\\Documents\\NetBeansProjects\\BankFile_assignment.txt");
ObjectOutputStream oos=new ObjectOutputStream(fos);
oos.writeObject(accounts);//take the arrayList
oos.flush();
oos.close();
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
public List<BankAccount> readFromFile(){
List<BankAccount>readData=null;
try {
FileInputStream fis=new FileInputStream("C:\\Users\Documents\\NetBeansProjects\\BankFile_assignment.txt");
ObjectInputStream ois=new ObjectInputStream(fis);
//make an arrayList to get those object back
//arrayList
readData=(List<BankAccount>)ois.readObject();
ois.close();
fis.close();
} catch (Exception e) {
e.printStackTrace();
}
//return readData;
return readData;
}
}
的BankAccount：
package bankapp_assignment;
import java.io.Serializable;
public class BankAccount implements Serializable{
private String name;
private int accNum;
private double initiateAmount;
//constructor
public BankAccount() {
this.name = null;
this.accNum = 0;
this.initiateAmount = 0;
}
public void setName(String name) {
this.name = name;
}
public void setAccNum(int accNum) {
this.accNum = accNum;
}
public String getName(String name){
return name;
}
public int getAccNum() {
return accNum;
}
public void setInitiateAmount(double initiateAmount) {
this.initiateAmount = initiateAmount;
}
public double getInitialAmount(){
return initiateAmount;
}
@Override
public String toString() {
return name + "\t\t" + accNum + "\t\t" + initiateAmount;
}
}