Computer Science 252
Problem Solving with Java
Fall 2013, The College of Saint Rose
ATM3 Demo
A working demo of ATM3 will appear below. Click inside the applet to interact with it.
ATM3 BlueJ Project
Click here to download a BlueJ project for ATM3.
ATM3 Source Code
The Java source code for ATM3 is below. Click on a file name to download it.
/* $Id: ATM.java 2269 2013-12-01 02:33:37Z terescoj $ */
/**
* Class to represent ATM which withdraws money from a bank
* Written 11/26/99 by Kim Bruce
* Changed 3/16/00 by Barbara Lerner
* Introduced a random pause in the critical section to make interference more probable.
* Changed 5/7/02 by Jim Teresco to include a longer delay to better see
* what is happening
*
* @author additional updates, Jim Teresco, Siena College, Spring 2011
* Additional updates, CSC 252, The College of Saint Rose, Fall 2013
*
*/
import java.util.Random;
import javax.swing.JLabel;
public class ATM extends Thread {
private static final int MAX_PAUSE = 10;
private static final int NUM_TRANSACTIONS = 1000;
private Random pauseGenerator = new Random();
private Account account;
private int change; // Amount of each transaction
private JLabel info; // Where to display description of transactions
private int total = 0;
// Store parameters and start running
public ATM(Account anAccount, int aChange, JLabel aInfo) {
account = anAccount;
change = aChange;
info = aInfo;
start();
}
// Repeatedly withdraw "change" from account at bank.
// This is effectively a deposit when "change" is negative.
public void run() {
for (int i = 0; i < NUM_TRANSACTIONS; i++) {
account.changeBalance(change);
total = total + change;
info.setText("" + total);
// demonstrate both with and without sleep
//try {
// sleep(400);
//}
//catch (Exception e) {}
}
}
}
/* $Id: Bank.java 2269 2013-12-01 02:33:37Z terescoj $ */
/*
* Class that represents a bank with two ATM's making deposits and withdrawals.
* This program was designed to illustrate problems with concurrency.
* Written 11/26/99 by Kim Bruce.
* Changed 3/16/99 by Barbara Lerner to use a different UI showing just current values, not
* a transaction history.
*
* @author updated by Jim Teresco, Siena College, Spring 2011
* Further updated for Swing and to remove dependency on Objectdraw
* by Jim Teresco, The College of Saint Rose, Fall 2013, CSC 252
*/
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JPanel;
// note that since this class does not need ObjectDraw but does have Java Swing
// components, we extend "JApplet" instead of "WindowController"
public class Bank extends JApplet implements ActionListener {
private static final int INITIAL_BALANCE = 1000; // Initial balance in bank account
private static final int TRANSACTION_AMOUNT = 100; // how much to deposit/withdraw per xaction
private JLabel currentBalanceLabel;
private JLabel withdrawTotalLabel;
private JLabel depositTotalLabel;
// Set up window layout and two ATM threads
// The init method is the JApplet equivalent of a WindowController's begin method
public void init() {
JLabel startBalance = new JLabel("Starting balance: " + INITIAL_BALANCE, JLabel.CENTER);
JLabel currentLabel = new JLabel("Current balance: ", JLabel.RIGHT);
currentBalanceLabel = new JLabel("" + INITIAL_BALANCE + " ", JLabel.LEFT);
JLabel withdrawLabel = new JLabel("Amount withdrawn: ", JLabel.RIGHT);
withdrawTotalLabel = new JLabel(" 0 ", JLabel.LEFT);
JLabel depositLabel = new JLabel("Amount deposited: ", JLabel.RIGHT);
depositTotalLabel = new JLabel(" 0 ", JLabel.LEFT);
setLayout(new GridLayout(0, 1));
this.setFont(new Font("System", Font.PLAIN, 18));
add(startBalance);
JPanel balancePanel = new JPanel();
balancePanel.add(currentLabel);
balancePanel.add(currentBalanceLabel);
add(balancePanel);
JPanel withdrawPanel = new JPanel();
withdrawPanel.add(withdrawLabel);
withdrawPanel.add(withdrawTotalLabel);
add(withdrawPanel);
JPanel depositPanel = new JPanel();
depositPanel.add(depositLabel);
depositPanel.add(depositTotalLabel);
add(depositPanel);
JPanel buttonPanel = new JPanel();
JButton runIt = new JButton("Run demo");
buttonPanel.add(runIt,"South");
add(buttonPanel);
runIt.addActionListener(this);
}
// Run the demo each time the button is pressed.
public void actionPerformed(ActionEvent evt) {
Account account = new Account(INITIAL_BALANCE, currentBalanceLabel);
ATM atm1 = new ATM(account, 100, depositTotalLabel);
ATM atm2 = new ATM(account, -100, withdrawTotalLabel);
}
}
import javax.swing.JLabel;
/* $Id: Account.java 2269 2013-12-01 02:33:37Z terescoj $ */
/**
* A simple bank account. This one is safe for concurrent access by
* adding the sychronized keyword as needed.
*
* @author original unknown
* Updated for Java Swing, Jim Teresco, The College of Saint Rose, Fall 2013
*/
public class Account {
private int balance;
private JLabel display; // label on screen for balance
public Account(int start, JLabel aDisplay) {
balance = start;
display = aDisplay;
display.setText("" + balance);
}
synchronized public int getBalance() {
return balance;
}
synchronized public void changeBalance(int amount) {
balance = balance + amount;
display.setText("" + balance);
// alternate:
//int newBalance = balance + amount;
//display.setText("" + newBalance);
//balance = newBalance;
}
}