Creating a transfer function for a ATM simulation

Hi guys, im fairly new to java so im not sure on what to do here. What i want to be able to do is be able to transfer say $100 from this account to another account.I have attached the code below.Any help would be greatly appreciated. =).
Attachment 1728

Please paste the code in code tags instead. Many people will be hesitant with attachments. To add code tags type

[code]
YOUR CODE HERE
[/code]

Oh ok then. =)




[ATM GUI]
/* ATM.java requires: ATMLogin.java ATMDataFile.java
ATMData.txt*/

Code:

---

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;


public class ATM {
    static JFrame ATMFrame = new JFrame("ATM");

  // ATM constructor 
    public ATM() throws IOException {
        // Instantiate a new ATMDataFile object called atmData
        ATMDataFile atmData = new ATMDataFile();
        loginGUI();
        ATMFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        ATMFrame.setSize(400,200);
}

  public static void loginGUI() {         
    //Create and set up the ATM Login content pane.
    final ATMLogin loginContentPane = new ATMLogin(ATMFrame);
    ATMFrame.setContentPane(loginContentPane);

    //Make sure the focus goes to the right component
    //whenever the ATMFrame is initially given the focus.
    ATMFrame.addWindowListener(new WindowAdapter() {
      public void windowActivated(WindowEvent e) {
        loginContentPane.resetFocus();
      }
    });     
    //Display the pane.
    ATMFrame.setVisible(true);
  }

  public static void chooserGUI() { 
    //Create and set up the ATM Login content pane.
    final ATMChooser chooserPane = new ATMChooser(ATMFrame);
    ATMFrame.setContentPane(chooserPane);
    //Display the window.
    ATMFrame.setVisible(true);
  }

  public static void withdrawGUI() {         
    //Create and set up the ATM Login content pane.
    final ATMWithdraw withdrawContentPane = new ATMWithdraw(ATMFrame);
    withdrawContentPane.setLayout(new GridLayout(0,1));
    ATMFrame.setContentPane(withdrawContentPane);     
    //Display the window.
    ATMFrame.setVisible(true);
  }
 
  public static void depositGUI() {         
    //Create and set up the ATM Login content pane.
    final ATMDeposit depositContentPane = new ATMDeposit(ATMFrame);
    depositContentPane.setLayout(new GridLayout(0,1));
    ATMFrame.setContentPane(depositContentPane);     
    //Display the window.
    ATMFrame.setVisible(true);
  }
 
  public static void transferGUI() {         
    //Create and set up the ATM Login content pane.
    final ATMTransfer transferContentPane = new ATMTransfer(ATMFrame);
    transferContentPane.setLayout(new GridLayout(0,1));
    ATMFrame.setContentPane(transferContentPane);     
    //Display the window.
    ATMFrame.setVisible(true);
    }

  public static void balanceGUI() {
    //Create and set up the ATM Login content pane.
    final ATMBalance balanceContentPane = new ATMBalance(ATMFrame);
    balanceContentPane.setLayout(new GridLayout(3,1));
    ATMFrame.setContentPane(balanceContentPane);
    //Display the window.
    ATMFrame.setVisible(true);
  }

  public static void main(String[] args) throws IOException {
    ATM atm = new ATM();
  } 
}

---

[ATMDataFile]/* ATMDataFile Loads bank account data from a text file into memory
for use by other objects that change things (balance etc).
If no text file exists one is created with details for one account.
Data is held by a two dimensional array (account_inf[][]) where
account_inf[0][0] is 1st account number
account_inf[0][1] is 1st account pasword
account_inf[0][2] is 1st account balance
account_inf[1][0] is 2nd account number
account_inf[1][1] is 2st account pasword etc...*/

Code:

---

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

public class ATMDataFile {
  public static String datafilename = "ATMData.txt";
  public static int lines = 0; // Number of lines in ATMdata.txt
  public static int lineNo; // Line number of the opperative account
  // Create a File object called "datafile" to see if "ATMdata.txt" exists
  static File datafile = new File(datafilename);
  // Declare a 2 dimensional array to hold account details
  // First three values are only used if no datafile exists.
  static String[][] account_inf = {{"John","Savings","12345","4444","100"},
                                      {"Jack","Manager","54321","0000","100"},
                                      {null,null,null},
                                      {null,null,null},
                                      {null,null,null}}; 

  public ATMDataFile() throws IOException {
    // If ATMdata.txt exists run loadData method               
    if (datafile.exists()) {
      loadData();
      // Debug code
      //writeFile();
      // If no datfile exists run the writeNewFile method
    } else {
        writeNewFile();
    }
  }

  // method for loading ATMdata.txt to a 2 dimensional array
  static void loadData()throws IOException {
    Scanner scan = null;
    BufferedReader read = null;
    try {
      // Create Scanner (reads text files one space delimeted element at a time)
      // and BufferedReader (reads contents of a text file into memory) objects
      scan = new Scanner(new BufferedReader(new FileReader(datafile.getName())));
      read = new BufferedReader(new FileReader(datafile.getName()));
      // Count the number of lines in ATMdata.txt
      String l;
      while ((l = read.readLine()) != null) {
          lines ++ ;
      }
      // Debug code
      System.out.println ("Lines =" +lines);
      // Populate the 2 dimensional array account_inf with contents of
      // ATMdata.txt. account_inf[0][0] is 1st account number
      //              account_inf[0][1] is 1st account pasword
      //              account_inf[0][2] is 1st account balance 
      //              account_inf[1][0] is 2nd account number etc...
      for(int i=0; i<=lines-1; i++){
        for(int j=0; j<=4; j++){
          account_inf[i][j] = scan.next();
          // Debug code
          System.out.print(" [" +i +"][" +j +"]="
                              +account_inf[i][j]);
        }
        // Debug code     
        System.out.println();
      }               
    } catch (IOException e) {
      System.err.println("Caught IOException: "
                              +  e.getMessage());
      } finally {
        if (scan != null) {
            scan.close();
        }
      }
    }

  static void writeNewFile()throws IOException {
    String name = account_inf[0][0];
    String account_typ = account_inf[0][1];
    String account_no = account_inf[0][2];
    String password = account_inf[0][3];
    String balance = account_inf[0][4];
    PrintWriter out = null;
    try {
      // Create an output stream to write to ATMdata.txt
      out = new PrintWriter(datafile.getName());
      // Write the first three values of the two dimensional array
      // to the ATMdata.txt file.
    out.format ("%s %s %s %s %s", account_inf[0][0], account_inf[0][1], account_inf[0][2], account_inf[0][3], account_inf[0][4]);
    } finally {
      if (out != null) { 
        out.close();
      }
    }
  } 
   
  static void writeFile()throws IOException {
    PrintWriter out = null;
    try {
      // Create an output stream to write to ATMdata.txt
      out = new PrintWriter(datafile.getName());
      // Write account_inf[][] to disk
      for (int i = 0; i<=lines-1; i++) {
        out.format ("%s %s %s %s %s", account_inf[i][0],
                                account_inf[i][1],
                                account_inf[i][2],
                                account_inf[i][3],
                                account_inf[i][4]);
                               
        out.println();
      }                       
    } finally {
      if (out != null) { 
        out.close();
      }
    }
  } 
   
  static String getPin(String account_id){
    String pin = "";
    for (int i = 0; i <= lines ; i++) {
      if (account_id.equals(account_inf[i][2])) {
              pin = account_inf[i][3];
              lineNo = i;
              // Debug code
        System.out.println("pinString="+pin);
        break;
      }
    }   
   
    return pin;   
  }
 
  static String doDeposits(String amount){
    // Deposit cash -- called from ATMDeposits
    String newBalance = "";
    // Turn Strings to doubles for arithmatic
    double depositsAmount=               
        (new Double(amount)).doubleValue();
    double currentBalance=
        (new Double(account_inf[lineNo][4])).doubleValue();
    // Get the new balance as a string & update the account_inf array   
      newBalance = Double.toString
                    (currentBalance + depositsAmount);
      account_inf[lineNo][4] = newBalance;   
   
    return newBalance;   
  }
 
 
 
  static String doWithdrawl(String amount){
    // Withdraw cash -- called from ATMWithdrawl
    String newBalance = "";
    // Turn Strings to doubles for arithmatic
    double withdrawlAmount=               
        (new Double(amount)).doubleValue();
    double currentBalance=
        (new Double(account_inf[lineNo][4])).doubleValue();
    // Get the new balance as a string & update the account_inf array   
      newBalance = Double.toString
                    (currentBalance - withdrawlAmount);
      account_inf[lineNo][4] = newBalance;   
   
    return newBalance;   
  }

  static String doTransfer(String amount){
    // Withdraw cash -- called from ATMWithdrawl
    String newBalance = "";
    // Turn Strings to doubles for arithmatic
    double transferAmount=               
        (new Double(amount)).doubleValue();
    double currentBalance=
        (new Double(account_inf[lineNo][4])).doubleValue();
    // Get the new balance as a string & update the account_inf array   
      newBalance = Double.toString
                    (currentBalance - transferAmount);
      account_inf[lineNo][4] = newBalance;   
   
    return newBalance;   
  }
  static String getBalance() {
    return account_inf[lineNo][4];
  }

}

---

[ATMTransfer]/*+++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++
*DESCRIPTION:
*ATMTransfer is a subtype of the Java JPanel class which is a GUI
* container which is contained by a JFrame (ATM) and contains the
* Text, buttons and entry fields of the GUI.
*
* CALLED BY:
* Clicking the Transferl button on the ATMChooser JPanel object calls the
* ATMTransferl method on the ATM object which in turn invokes this class
*
* ACTIONS:
* The ATMTransfer JPanel allows the user to select an ammount to Transfer
* by either mouse clicking on an ammount button or typing in an amount to
* Transfer.
*
* CALLS:
* This class calls the doTransferl method on the ATMData object to action
* the Transferl then calls the balanceGUI method on the ATM object to display
* the new balance.
++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++*/

Code:

---

// Import GUI, IO and math libraries
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.math.*;

// Class declaration establishing ATMTransfer as a subtype of
//  JPanel (a content pane to be displayed inside a JFrame)
//  elements of a graphic user interface (GUI)
//  impliments ActionListener statement indicates that it uses
//  the Java actionlistener class
public class ATMTransfer extends JPanel
                      implements ActionListener {
// Declare string variables for use in GUI
    private static String AU20 = "20";
    private static String AU50 = "50";
    private static String AU100 = "100";
    private static String AU200 = "200";
    private static String AU300 = "300";
    private static String OTHER = "other";
    private static String AMOUNT = "amount";
    private static String ACCOUNT_INF = "account_inf";
// Declare JButton variables for use in GUI   
    private static JButton au20Button, au50Button, au100Button,
                            au200Button,au300Button, otherButton;
// Declare object variables for use in GUI
    private JFrame controllingFrame; //needed for dialogs
    protected JTextField amountTextField;
    protected JTextField account_infTextField;
    protected JLabel amountLabel;
    protected JLabel account_infLabel;
   
    private ATMDataFile atmData;
    private ATM atm;
 
// Constructor method - called from ATM with ATMframe as the argument f
// an ATMTransferl object is created as a subtype of a JPanel
    public ATMTransfer(JFrame f) {
        controllingFrame = f;
        JComponent titlePane = createTitlePane();
        add(titlePane);    // add the titlepane to the ATMTransfer JPanel
  // Call the createButtonPanel method to populate the button pane       
        JComponent buttonPane = createButtonPanel();
        add(buttonPane);
  // Call the createBotTextPane method to populate the text box pane pane
        JComponent botTextPane = createBotTextPane();
        add(botTextPane);
        add(botTextPane);
    }

// "actionPerformed" method - reads the action command "cmd"
//    set by the button and text field components and selected
//    by the users mouse click or text entry
//    and selects the action to perform
    public void actionPerformed(ActionEvent e) {
        String cmd = e.getActionCommand(); //gets "cmd" if button clicked
        String input = amountTextField.getText(); //gets "input" from text entry
        if (OTHER.equals(cmd)){            // Other amount button pressed.
          amountTextField.setEnabled(true);
          amountTextField.setEnabled(true);// enable text entry
          amountLabel.setEnabled(true);
          account_infTextField.setEnabled(true);
          account_infLabel.setEnabled(true);
          au20Button.setEnabled(false);    // disable (grey out) other buttons
          au50Button.setEnabled(false);
          au100Button.setEnabled(false);
          au200Button.setEnabled(false);
          au300Button.setEnabled(false);
          otherButton.setEnabled(false);
          amountTextField.requestFocusInWindow();  //set focus to text entry
        } else if (AMOUNT.equals(cmd)) {          // User enters other amount.
            //Test if the entered ammount is a multiple of $20
            // by using the "mod" opperation to divide by 20 and find the remainder
            BigInteger remainder = (new BigInteger(input)).mod
                                    (new BigInteger("20"));
            // Test if remainder is "0"
            if (remainder.equals((new BigInteger("0")))) {    // Yes it's a multiple
              JOptionPane.showMessageDialog(controllingFrame, // pop up a success message
                    "$"+input +" is a multiple of $20\n"
                    +"Well done!!");
              // Invoke the "tryTransfers" method
              //  with the entered ammount as the argument     
              tryTransfers(input); 
             
            } else {                                        // Not a multiple of $20
                JOptionPane.showMessageDialog(controllingFrame,  // pop up a failure message
                    "$"+input +" is not a multiple of $20\n"
                    +"This is not a multiple of $20,Please try again.",
                    "Error Message",
                    JOptionPane.ERROR_MESSAGE);         
            }
        } else {        // User pressed a value button
            int buttonValue = (new Integer(cmd)).intValue();
            switch (buttonValue) {
                case 20:  tryTransfers(cmd); break;
                case 50:  tryTransfers(cmd); break;
                case 100:  tryTransfers(cmd); break;
                case 200:  tryTransfers(cmd); break;
                case 300:  tryTransfers(cmd); break;
              } 
          }             
    }

// "tryTransferl" method calls ATMData.doTransferl and process results
    protected void tryTransfers(String in) {
    // run the doTransferl method on the ATMData object
    // this method returns the amount remaining in the account
    // which is stored in the newBalance variable
    String newBalance = atmData.doTransfer(in);

      if (newBalance.isEmpty()) {          //Not enough cash
          // Display an error message
          JOptionPane.showMessageDialog(controllingFrame,
                    "You don't have $"+in +" to Transfer.\n"
                    +"Sorry mate please try again.",
                    "Error Message",
                    JOptionPane.ERROR_MESSAGE);
      } else {                              // Transferl OK
          // Go back to the balance display screen by invoking the
          // balanceGUI method on the atm object
          atm.balanceGUI();     
      }
    }   

// Methods to populate the title pane, button pane
//  and bottom text entry pane with text, buttons and
//  text entry components. These methods are called from the
//  class constructor method which also adds them to the atm frame.
//  These are written as seperate methods to seperate the "messy and confusing"
//  GUI componentry from the actual processes conducted by this class.
 
    protected JComponent createTitlePane() {
        JPanel t = new JPanel(new GridLayout(0,1));

        JLabel topLabel = new JLabel("Select amount to Transfer: ");
        t.add(topLabel);
       
        return (t);
    }

       
    protected JComponent createButtonPanel() {
        JPanel p = new JPanel(new GridLayout(0,2));

        au20Button = new JButton("$20");
        au20Button.setActionCommand(AU20);
        au20Button.addActionListener(this);
        p.add(au20Button);

        au200Button = new JButton("$200");
        au200Button.setActionCommand(AU200);       
        au200Button.addActionListener(this);
        p.add(au200Button);
       
        au50Button = new JButton("$50");
        au50Button.setActionCommand(AU50);     
        au50Button.addActionListener(this);
        p.add(au50Button);

        au300Button = new JButton("$300");
        au300Button.setActionCommand(AU300); 
        au300Button.addActionListener(this);       
        p.add(au300Button);
       
        au100Button = new JButton("$100");
        au100Button.setActionCommand(AU100);       
        au100Button.addActionListener(this);
        p.add(au100Button);
           
        otherButton = new JButton("Choose another amount");
        otherButton.setActionCommand(OTHER);
        otherButton.addActionListener(this);
        p.add(otherButton);

        return p;
    }
   
    protected JComponent createBotTextPane() {
        JPanel b = new JPanel(new FlowLayout(FlowLayout.TRAILING)); 

        amountTextField = new JTextField(5);
        amountTextField.setActionCommand(AMOUNT);
        amountTextField.addActionListener(this);
        amountTextField.setEnabled(false);
       
        amountLabel = new JLabel("Type Transfer amount (multiples of $20 only)");
        amountLabel.setLabelFor(amountTextField);
        amountLabel.setEnabled(false);

        account_infTextField = new JTextField(8);
        account_infTextField.setActionCommand(ACCOUNT_INF);
        account_infTextField.addActionListener(this);
        account_infTextField.setEnabled(true);
       
        account_infLabel = new JLabel("Enter the account number");
        account_infLabel.setLabelFor(account_infTextField);
        account_infLabel.setEnabled(true);
       
        b.add(amountLabel);
        b.add(amountTextField);
        b.add(account_infLabel);
        b.add(account_infTextField);


        return (b);
    }
}

---

You also will get more help by explaining what exactly is challenging you. Perhaps a SSCCE will also help here. Most likely not many people will read through so much code.

Well what im trying to do is be able to transfer say $100 from one account to another, but i have no clue on what type of method to use...

You should really have an Account class, rather than a 2d array which creates the accounts. Then the account class can have a method like

Code:

---

public void transferMoney(int amount, Account from, Account to){...}

---

Hmm good point, but if i were to create a separate class for the accounts that would mean the code would need to be dramatically changed? hahaha excuse my beginner talk =/

The code will have to be changed yes, but it's a good way to learn. Making your code as object based as possible(oop), makes for easier to maintain, change, and fix code errors.

I've become a bit lost where to start ='(

Try creating an Account class which has all the information about the account, and methods to do whatever is necessary to the account, deposit, withdraw, checkBalance, transfer, etc

Then the GUI will basically be used to manage accounts.

Would it be like as below?

[Account]

Code:

---

import java.util.Scanner;
public class Account {
        private String accountName;
        private int password;
        private double balanceAmount;
        private static int accountNumberCounter = 100;
        private int accountNumber;
 
        Scanner userInput = new Scanner(System.in);
        Account bob = new Account("Jake Styles", 1111, 100.00);
        Account mary = new Account("Jenny Smith", 2222, 200.00);
        Account sally = new Account("John Green", 1111, 300.00);
       
        public Account(String name, int pword, double balance) {
                accountName = name;
                password = pword;
                balanceAmount = balance;
                accountNumberCounter++;
                accountNumber = accountNumberCounter;
 
                // This shows we have brought the information over from the BankApp class
                System.out.println(accountName + " " + password + " " + balanceAmount);
                System.out.println("Option " + BankApp.option + " was selected.");
 
        }
 
        public int acctNum() {
                return accountNumber;
        }
 
        public double getBalance() {
                return balanceAmount;
 
        }
 
        public void setBalance(double balance) {
                balanceAmount = balance;
 
        }
 
        public void withdraw(double withdrawAmount) {
                if (withdrawAmount > balanceAmount) {
                        System.out
                                        .println("You do not have enough money in your account, try again");
                } else {
                        balanceAmount = balanceAmount - withdrawAmount;
                }
 
        }
 
        public void deposit(double depositAmount) {
                balanceAmount = balanceAmount + depositAmount;
        }
 
}

---

Looks good, although I would be hesitant about allowing so much freedom in the setBalance method. What if some creep decided to come along and do

Code:

---

account.setBalance(Integer.MIN_VALUE);

---

?

Perhaps you can limit the account balances changes. For example, you could provide the following three methors

Code:

---

public void deposit(int amount){...}
public void withdraw(int amount){...}
public void transfer(Account from, Account to, int amount){...}

---

This way you can check what is being done to the account. Perhaps if someone tries something like

Code:

---

account.deposit(Integer.MIN_VALUE);

---

you can do something like

Code:

---

public void deposit(int amount){
  if(! amount > 0) throw new IllegalArgumentException("Can't deposit negative amounts");
  ...
}

---

This way the only balance changes will be made from within the class in the way you want it to happen.

So my suggestion: get rid of the setter, and add these three methods I've provided to you. You may want to get rid of the 3 instances of the account which are instance variables of the class, since they aren't really members of account. When you develop ATMMachine(or whatever it ends up being named), it will create the Accounts and manage them.

Hey mate, thankyou for the advice =). Below is the updated code based on your advice, i have added the three methods however when i go to compile the code I get '.class' expected. I assume i have made a beginner mistake? p.s i have marked the line in red

[Account]

Code:

---

public class Account {
    private String accountName;
    private int password;
    private double balanceAmount;
    private static int accountNumberCounter = 100;
    private int accountNumber;
 
       
    public Account(String name, int pword, double balance) {
        accountName = name;
        password = pword;
        balanceAmount = balance;
        accountNumberCounter++;
        accountNumber = accountNumberCounter;
 
        // This shows we have brought the information over from the BankApp class
        System.out.println(accountName + " " + password + " " + balanceAmount);
        System.out.println("Option " + BankApp.option + " was selected.");
 
    }
 
    public int acctNum() {
        return accountNumber;
    }
 
    public double getBalance() {
        return balanceAmount;
 
    }
 
    public void withdraw(int amount) {
        [COLOR="red"]if (int) amount > balanceAmount) {[/COLOR]
            System.out
                    .println("You do not have enough money in your account, try again");
        } else {
            balanceAmount = balanceAmount - ! amount;
        }
 
    }
 
    public void deposit(int amount) {
        balanceAmount = balanceAmount + "int amou";
        if(! amount > 0) throw new IllegalArgumentException("Can't deposit negative amounts")
    }
   
    public void transfer(Account from, Account to, int amount)


}

---

Code:

---

public void withdraw(int amount) {
        if (int) amount > balanceAmount) {
            System.out
                    .println("You do not have enough money in your account, try again");
        } else {
            balanceAmount = balanceAmount - ! amount;
        }
 
    }
 
    public void deposit(int amount) {
        balanceAmount = balanceAmount + "int amou";
        if(! amount > 0) throw new IllegalArgumentException("Can't deposit negative amounts")
    }

---

Evaluate the code. Does this look correct

Code:

---

if (int) booleanExpression)

---

Scrutinize this section and you will notice something wrong.

When it comes to the deposit code

Code:

---

if(! amount > 0) throw new IllegalArgumentException("Can't deposit negative amounts")

---

Must be the first thing the code tests. Why bother continuing if they tried to deposit an incorrect number? You also don't need to use an exception, you can use a simple print method, but you have to be careful that you don't continue with modifying the account balance.

Ok i have fixed that problem =) any idea how i would write the method for the transfer function?