Multithreading in Java | #51 | ReentrantLock with Condition Interface | newcondition() Method

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Codes: note - Angled Brackets are not allowed in the video description.





Shared.java


class Shared
{
private int i =0;
void add()
{
i=i+1;
}
void sub()
{
i=i-1;
}
int currentValue()
{
return i;
}
}


Check.java


import java.util.concurrent.locks.*;
class Check
{
public static void main(String[] args)
{
ReentrantLock l = new ReentrantLock();
Condition inc = l.newCondition();
Condition dec = l.newCondition();
Shared s = new Shared();
MyThread t1 = new MyThread("t1",l,s,inc,dec);
MyThread t2 = new MyThread("t2",l,s,inc,dec);
t1.start();
t2.start();
}
}


MyThread.java


import java.util.concurrent.*;
import java.util.concurrent.locks.*;
public class MyThread extends Thread
{
ReentrantLock lock = null;
Shared s = null;
Condition inc = null;
Condition dec = null;

public MyThread(String name, ReentrantLock lock, Shared s, Condition inc, Condition dec)
{
super(name);
this.lock=lock;
this.s=s;
this.inc = inc;
this.dec = dec;
}


public void increase() throws Exception
{
lock.lock();
System.out.println(Thread.currentThread().getName()+": Got the lock");
while(s.currentValue() le 99)
{
if(s.currentValue() == 20) //spurious wakeup
{
System.out.println(Thread.currentThread().getName()+" releasing lock without calling unlock() method ");
inc.await();
System.out.println(Thread.currentThread().getName()+" got lock again without calling lock() method ");
}
s.add();
System.out.println(Thread.currentThread().getName()+" increases the value of i to "+s.currentValue());
if(s.currentValue()==20)
{
System.out.println(Thread.currentThread().getName()+" signals other ");
dec.signalAll();
}
}
lock.unlock();
System.out.println(Thread.currentThread().getName()+": Release the lock");
}

public void decrease() throws Exception
{
lock.lock();
System.out.println(Thread.currentThread().getName()+": Got the lock");
while(s.currentValue() le 99)
{
if(s.currentValue() == 0)
{
System.out.println(Thread.currentThread().getName()+" releasing lock without calling unlock() method ");
dec.await();
System.out.println(Thread.currentThread().getName()+" got lock again without calling lock() method ");
}
s.sub();
System.out.println(Thread.currentThread().getName()+" decreases the value of i to "+s.currentValue());
if(s.currentValue()==0)
{
System.out.println(Thread.currentThread().getName()+" signals other "+inc);
inc.signalAll();
}
}
lock.unlock();
System.out.println(Thread.currentThread().getName()+": Release the lock");
}

public void run()
{
try
{
if(Thread.currentThread().getName()=="t1")
{
increase();
}
if(Thread.currentThread().getName()=="t2")
{
decrease();
}
}
catch(Exception e){System.out.println(e);}
}
}