Producer-Consumer Inter-thread communication
Table.java
public class Table
{
private String obj;
private boolean empty = true;
public synchronized void put(String obj)
{
if(!empty)
{ try
{ wait();
}catch(InterruptedException e)
{ e.printStackTrace(); }
}
this.obj = obj;
empty = false;
System.out.println(Thread.currentThread().getName()+" has put "+obj);
notify();
}
public synchronized void get()
{
if(empty)
{ try
{ wait();
}catch(InterruptedException e)
{ e.printStackTrace(); }
}
empty = true;
System.out.println(Thread.currentThread().getName()+" has got "+obj);
notify();
}
public static void main(String[] args)
{
Table table = new Table();
Runnable p = new Producer(table);
Runnable c = new Consumer(table);
Thread pthread = new Thread(p, "Producer");
Thread cthread = new Thread(c, "Consumer");
pthread.start(); cthread.start();
try{ pthread.join(); cthread.join(); }
catch(InterruptedException e){ e.printStackTrace(); }
}
}
Producer.java
public class Producer implements Runnable
{ private Table table;
public Producer(Table table)
{ this.table = table; }
public void run()
{ java.util.Scanner scanner = new java.util.Scanner(System.in);
for(int i=1; i <= 5; i++)
{ System.out.println("Enter text: ");
table.put(scanner.next());
try{ Thread.sleep(1000); }
catch(InterruptedException e){ e.printStackTrace(); }
}
}
}
Consumer.java
public class Consumer implements Runnable
{
private Table table;
public Consumer(Table table)
{ this.table = table; }
public void run()
{ for(int i=1; i <= 5; i++){
table.get();
}
}
}
Inter-thread Synchronization example
Users.java
public class Users implements Runnable
{ private Account ac;
public Users(Account ac)
{ this.ac = ac; }
public void run()
{
Thread t = Thread.currentThread();
String name = t.getName();
for(int i=1; i<=5; i++)
{
if (name.equals("John"))
{ ac.deposit(200); }
if (name.equals("Mary"))
{ ac.withdraw(200); }
}
}
}
Account.java
public class Account
{ private double balance;
public Account(double startBalance)
{ this.balance = startBalance; }
public synchronized void deposit(double amount)
{ Thread t = Thread.currentThread();
double bal = this.getBalance(); bal += amount;
try{ Thread.sleep(1000); }
catch(InterruptedException ie)
{ ie.printStackTrace(); }
this.balance = bal;
System.out.println(t.getName() + " has deposited "+amount); }
public synchronized void withdraw(double amount)
{ Thread t = Thread.currentThread();
if (this.getBalance()>=amount)
{ try{ Thread.sleep(1000); }
catch(InterruptedException ie)
{ ie.printStackTrace(); }
this.balance -= amount;
System.out.println(t.getName() + " has withdrawn "+amount);
}
}
public double getBalance() { return this.balance; }
}
AcTest.java
public class AcTest
{
public static void main(String[] args)
{
Account a = new Account(5000);
System.out.println("Current balance: "+a.getBalance());
Runnable john = new Users(a); Runnable mary = new Users(a);
Thread t1 = new Thread(john,"John"); Thread t2 = new Thread(mary,"Mary");
t1.start(); t2.start();
try{
t1.join(); t2.join();
}catch(InterruptedException ie)
{ ie.printStackTrace();
}
System.out.println("Current balance: "+a.getBalance());
}
}
Synchronization another example
Sync.java
public class Sync implements Runnable
{ private Display d;
private String message;
public Sync(Display d, String message)
{ this.d = d; this.message = message; }
public void run()
{ synchronized(d)
{ // or syncronize the show method
d.show(this.message);
}
}
public static void main(String[] args)
{ Display d = new Display();
Runnable r1 = new Sync(d, "First Message"); Runnable r2 = new Sync(d, "Second Message");
Runnable r3 = new Sync(d, "Third message");
Thread t1 = new Thread(r1); Thread t2 = new Thread(r2); Thread t3 = new Thread(r3);
t1.start(); t2.start();t3.start();
}
}
class Display
{ // public synchronized void show(String message)
public void show(String message)
{
System.out.print("{ " + message);
try{ Thread.sleep(500); }
catch(InterruptedException e){ e.printStackTrace(); }
System.out.println(" }");
}
}
