edu.pdx.cs.joy.net.SynchronizedATM Maven / Gradle / Ivy
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package edu.pdx.cs.joy.net;
/**
* This class demonstrates obtains a lock before access the
* BankAccount. That way, it always sees a consistent
* view of the account.
*/
public class SynchronizedATM extends ATM {
public SynchronizedATM(String name, BankAccount account,
int[] transactions) {
super(name, account, transactions);
}
/**
* Perform each transaction on the account
*/
public void run() {
for (int i = 0; i < transactions.length; i++) {
// Get the lock on the account
synchronized(account) {
// Get the balance
int balance = account.getBalance();
out.println(this.name + " got balance " + balance);
// Perform the operation
out.println(this.name + " perform " + transactions[i]);
balance += transactions[i];
// Set the balance
out.println(this.name + " set balance to " + balance);
account.setBalance(balance);
}
// Give up the lock
}
}
/**
* Create a couple of accounts and have them all perform the same
* transactions, but in different orders.
*/
public static void main(String[] args) {
BankAccount account = new BankAccount();
account.setBalance(1000);
out.println("Initial balance: " + account.getBalance());
// Make some ATMs
int[] trans1 = {-200, 400, 100, -300};
ATM atm1 = new SynchronizedATM("ATM1", account, trans1);
int[] trans2 = {400, 100, -300, -200};
ATM atm2 = new SynchronizedATM("ATM2", account, trans2);
int[] trans3 = {-300, -200, 100, 400};
ATM atm3 = new SynchronizedATM("ATM3", account, trans3);
// Make some threads and start them
Thread t1 = new Thread(atm1);
t1.start();
Thread t2 = new Thread(atm2);
t2.start();
Thread t3 = new Thread(atm3);
t3.start();
// Wait for all threads to finish
try {
t1.join();
t2.join();
t3.join();
} catch (InterruptedException ex) {
return;
}
out.println("Final balance: " + account.getBalance());
}
}