Here is an example of BankAccount using swing components which allow the user to withdraw and deposit amount and display the current balance.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class Account extends Frame {
Label lab=new Label(" ");
Label lab1=new Label(" ");
TextField t[]=new TextField [4];
Label l[]=new Label [4];
Button but=new Button("Create Account");
Button but1=new Button("Test Account");
BankAccount b;
Account(){
addWindowListener(new NewWindowAdapter());
setLayout(new GridLayout(2,0));
Panel p=new Panel();
Panel p1=new Panel();
p.setLayout(new GridLayout(5,2));
p.setBackground(Color.pink);
p1.add(lab1);
p1.add(lab);
l[0]=new Label("Enter Your Account Number");
l[1]=new Label("Enter Your Initial Balance");
l[2]=new Label("Deposit Amount");
l[3]=new Label("Withdraw Amount");
for(int i=0;i<4;i++){
t[i]=new TextField(10);
p.add(l[i]);
p.add(t[i]);
}
p.add(but);
p.add(but1);
but1.setVisible(false);
l[2].setVisible(false);
l[3].setVisible(false);
t[2].setVisible(false);
t[3].setVisible(false);
add(p);
add(p1);
p1.setBackground(Color.pink);
but.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent ae){
String des=JOptionPane.showInputDialog(null,"Deposit or Withdraw");
if(des.equals("Deposit")){
b=new BankAccount(Integer.parseInt(t[0].getText()),Integer.parseInt(t[1].getText()));
but1.setVisible(true);
l[2].setVisible(true);
l[3].setVisible(false);
t[2].setVisible(true);
t[3].setVisible(false);
but.setVisible(false);
l[0].setVisible(false);
l[1].setVisible(false);
t[0].setVisible(false);
t[1].setVisible(false);
lab1.setText("Account : "+b.accnum+", Current Balance : "+b.amount);
but1.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent ae){
lab.setText(testAccount1(Integer.parseInt(t[2].getText())));
lab1.setText("Account : "+b.accnum+", Current Balance : "+b.amount);
}
});
}
else if(des.equals("Withdraw")){
b=new BankAccount(Integer.parseInt(t[0].getText()),Integer.parseInt(t[1].getText()));
but1.setVisible(true);
l[2].setVisible(false);
l[3].setVisible(true);
t[2].setVisible(false);
t[3].setVisible(true);
but.setVisible(false);
l[0].setVisible(false);
l[1].setVisible(false);
t[0].setVisible(false);
t[1].setVisible(false);
lab1.setText("Account : "+b.accnum+", Current Balance : "+b.amount);
but1.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent ae){
lab.setText(testAccount2(Integer.parseInt(t[3].getText())));
lab1.setText("Account : "+b.accnum+", Current Balance : "+b.amount);
}
});
}
}
});
}
String testAccount1(int d_amt){
String msg;
b.deposit(d_amt);
msg="Transaction Succesful";
return msg;
}
String testAccount2(int w_amt){
String msg;
msg="Transaction Succesful";
try{
b.withdraw(w_amt);
}catch(FundsInsufficientException fe){
fe=new FundsInsufficientException(b.amount,w_amt);
msg=String.valueOf(fe);
}
return msg;
}
public static void main(String arg[]){
Account at=new Account ();
at.setTitle("Bank Account System");
at.setSize(500,300);
at.setVisible(true);
}
}
class NewWindowAdapter extends WindowAdapter{
public void windowClosing(WindowEvent we){
System.exit(0);
}
}

continue..

class BankAccount{
int accnum;
int amount;
BankAccount(int num,int amt){
accnum=num;
amount=amt;
}
public void deposit(int amt){
amount=amount+amt;
}
public void withdraw(int amt) throws FundsInsufficientException{
if(amt>amount)
throw new FundsInsufficientException(amount,amt);
else
amount=amount-amt;
}
}
class FundsInsufficientException extends Exception{
int balance;
int withdraw_amount;
FundsInsufficientException(int bal,int w_amt){
balance=bal;
withdraw_amount=w_amt;
}
public String toString(){
return "Your withdraw amount ("+withdraw_amount+") is more than the balance ("+balance+"). No withdrawal was recorded.";
}
}

For more information, visit the following link:

http://www.roseindia.net/tutorial/java/core/bankAccountApplication.html