Java Coding Assignment- Multi-Threading

package part2; //SynchronizedBuffer synchronizes access to a single shared integer. import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.ReentrantLock; import java.util.concurrent.locks.Condition; public class SynchronizedBuffer implements Buffer { // Lock to control mutually exclusive access to the buffer private Lock accessLock = new ReentrantLock(); // conditions to control reading and writing - synchronizing access between the threads private Condition canWrite = accessLock.newCondition(); //used by consumer to notify producer private Condition canRead = accessLock.newCondition(); //used by producer to notify consumer private int buffer = -1; // shared by producer and consumer threads - (-1) means invalid private boolean occupied = false; // whether buffer is occupied - contents same as last access // setter (mutator) method for producer to write into buffer public void set( int value ) { accessLock.lock(); // lock this object // output thread information and buffer information, then wait try { // while buffer is not empty, place thread in waiting state while ( occupied ) { System.out.println( "Producer tries to write." ); displayState( "Buffer full. Producer waits." ); canWrite.await();// wait until buffer is empty } // end while buffer = value; // set new buffer value // indicate producer cannot store another value // until consumer retrieves current buffer value occupied = true; displayState( "Producer writes " + buffer ); // signal thread waiting to read from buffer canRead.signal(); } // end try catch ( InterruptedException exception ) { exception.printStackTrace(); } // end catch finally { accessLock.unlock(); // unlock this object } // end finally } // end method set // getter (accessor) method for consumer to retrieve value from buffer public int get() { int readValue = 0; // initialize value read from buffer accessLock.lock(); // lock this object // output thread information and buffer information, then wait try { // while no data to read, place thread in waiting state while ( !occupied ) { System.out.println( "Consumer tries to read." ); displayState( "Buffer empty. Consumer waits." ); canRead.await(); // wait until buffer is full } // end while // indicate that producer can store another value // because consumer just retrieved buffer value occupied = false; readValue = buffer; // retrieve value from buffer displayState( "Consumer reads " + readValue ); // signal thread waiting for buffer to be empty canWrite.signal(); } // end try // if waiting thread interrupted, print stack trace catch ( InterruptedException exception ) { exception.printStackTrace(); } // end catch finally { accessLock.unlock(); // unlock this object } // end finally return readValue; } // end method get // display current operation and buffer state public void displayState( String operation ) { System.out.printf( "%-40s%d\t\t\t\t%b\n", operation, buffer, occupied ); } // end method displayState } // end class SynchronizedBuffer