Problem in networking

Question

Dear all:
I am doing my homework. And I had solve the question 2.But in Q3, I spend about two weeks and cannot solve it. And the time is limited, pls. give me a hand. Thanks! The questions are:
(Q2) The system has a total of 10 threads. 5 threads are for generating random integers in the range 0 to 99 in random time intervals from 0 to 10 seconds. The generated integers are to be put into a buffer which can hold 3 integers. If the buffer is full, then the thread has to wait until a space is available. The other 5 threads are to get two integers from the buffer. The buffer is operated in the first in first out basis. The threads then print the sum of the two integers onto the screen.
(Q3) Modify the program in (2) so that the buffer becomes a server which accepts connections from the generating threads and summing threads. Stream sockets have to be used in the communication between the server and the threads.
My answer of Q2 is as follow for your reference:
public interface Buffer {
public void set( int value ); // place value into Buffer
public int get(); // return value from Buffer
import javax.swing.*;
public class CircularBuffer implements Buffer {
// each array element is a buffer
private int buffers[] = { -1, -1, -1 };
// occupiedBufferCount maintains count of occupied buffers
public int occupiedBufferCount = 0;
// variables that maintain read and write buffer locations
private int readLocation = 0, writeLocation = 0;
// reference to GUI component that displays output
private JTextArea outputArea;
// constructor
public CircularBuffer( JTextArea output )
outputArea = output;
} //end CircularBuffer
// place value into buffer
public synchronized void set( int value )
// for output purposes, get name of thread that called this method
String name = Thread.currentThread().getName();
// while there are no empty locations, place thread in waiting state
while ( occupiedBufferCount == buffers.length ) {
// output thread information and buffer information, then wait
try {
SwingUtilities.invokeLater( new RunnableOutput( outputArea,
"\nAll buffers full. " + name + " waits." ) );
wait();
} //end try
// if waiting thread interrupted, print stack trace
catch ( InterruptedException exception )
exception.printStackTrace();
} //end catch
} // end while
// place value in writeLocation of buffers
buffers[ writeLocation ] = value;
// update Swing GUI component with produced value
SwingUtilities.invokeLater( new RunnableOutput( outputArea,
"\n" + name + " writes " + buffers[ writeLocation ] + " ") );
// just produced a value, so increment number of occupied buffers
++occupiedBufferCount;
// update writeLocation for future write operation
writeLocation = ( writeLocation + 1 ) % buffers.length;
// display contents of shared buffers
SwingUtilities.invokeLater( new RunnableOutput(
outputArea, createStateOutput() ) );
notify(); // return waiting thread (if there is one) to ready state
} // end method set
// return value from buffer
public synchronized int get()
// for output purposes, get name of thread that called this method
String name = Thread.currentThread().getName();
// while no data to read, place thread in waiting state
while ( occupiedBufferCount == 0 ) {
// output thread information and buffer information, then wait
try {
SwingUtilities.invokeLater( new RunnableOutput( outputArea,
"\nAll buffers empty. " + name + " waits.") );
wait();
} //end try
// if waiting thread interrupted, print stack trace
catch ( InterruptedException exception ) {
exception.printStackTrace();
} //end catch
} // end while
// obtain value at current readLocation
int readValue = buffers[ readLocation ];
// update Swing GUI component with consumed value
SwingUtilities.invokeLater( new RunnableOutput( outputArea,
"\n" + name + " reads " + readValue + " ") );
// just consumed a value, so decrement number of occupied buffers
--occupiedBufferCount;
// update readLocation for future read operation
readLocation = ( readLocation + 1 ) % buffers.length;
// display contents of shared buffers
SwingUtilities.invokeLater( new RunnableOutput(
outputArea, createStateOutput() ) );
notifyAll(); // return all waiting thread to ready state
return readValue;
} // end method get
// create state output
public String createStateOutput()
// first line of state information
String output =
"(buffers occupied: " + occupiedBufferCount + ")\nbuffers: ";
for ( int i = 0; i < buffers.length; i++ )
output += " " + buffers[ i ] + " ";
// second line of state information
output += "\n ";
for ( int i = 0; i < buffers.length; i++ )
output += "---- ";
// third line of state information
output += "\n ";
// append readLocation (R) and writeLocation (W)
// indicators below appropriate buffer locations
for ( int i = 0; i < buffers.length; i++ )
if ( i == writeLocation && writeLocation == readLocation )
output += " WR ";
else if ( i == writeLocation )
output += " W ";
else if ( i == readLocation )
output += " R ";
else
output += " ";
output += "\n";
return output;
} // end method createStateOutput
} // end class CircularBuffer
import javax.swing.*;
public class RunnableOutput implements Runnable {
private JTextArea outputArea;
private String messageToAppend;
// initialize outputArea and message
public RunnableOutput( JTextArea output, String message )
outputArea = output;
messageToAppend = message;
} //end RunableOutput
// method called by SwingUtilities.invokeLater to update outputArea
public void run()
outputArea.append( messageToAppend );
} // end run
} // end class RunnableOutput
import javax.swing.*;
public class Producer extends Thread {
private CircularBuffer sharedLocation;
private JTextArea outputArea;
// constructor
public Producer(String name, CircularBuffer shared, JTextArea output)
super( name );
sharedLocation = shared;
outputArea = output;
} //end contructor
// store values in sharedLocation's buffer
public void run()
while(sharedLocation.occupiedBufferCount>=0){
// sleep 0 to 10 seconds, then place integer value 0 to 99 in Buffer
int value = ( int )(Math.random() * 99) ;
try {
Thread.sleep( ( int ) ( Math.random() * 10001 ) );
sharedLocation.set( value );
} //end try
// if sleeping thread interrupted, print stack trace
catch ( InterruptedException exception ) {
exception.printStackTrace();
} //end catch
} // end while
} // end method run
} // end class Producer
import javax.swing.*;
public class Consumer extends Thread {
private CircularBuffer sharedLocation; // reference to shared object
private JTextArea outputArea;
// constructor
public Consumer(String name, CircularBuffer shared, JTextArea output)
super( name );
sharedLocation = shared;
outputArea = output;
}// end constructor
// read sharedLocation's value two times and sum the values
public void run()
int sum = 0;
String name = getName();
while(sharedLocation.occupiedBufferCount>=0){
// read value from Buffer and add to sum
try {
int num1 = sharedLocation.get();
int num2 = sharedLocation.get();
sum = num1 + num2;
System.out.println(name + " Sum = " + sum);
} //end try
// if Exception, print stack trace
catch ( Exception exception ) {
exception.printStackTrace();
} //end catch
SwingUtilities.invokeLater( new RunnableOutput( outputArea,
"\nTotal " + name + " consumed: " + sum + ".\n"
} // end while
} // end method run
} // end class Consumer
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
// set up the producer and consumer threads and start them
public class JavaSystem extends JFrame {
JTextArea outputArea;
// set up GUI
public JavaSystem()
super( "TMA2 Q3" );
outputArea = new JTextArea( 20,30 );
outputArea.setFont( new Font( "Monospaced", Font.PLAIN, 12 ) );
getContentPane().add( new JScrollPane( outputArea ) );
setSize( 310, 500 );
setVisible( true );
// create shared object used by threads; we use a CircularBuffer reference
CircularBuffer sharedLocation = new CircularBuffer( outputArea );
// display initial state of buffers in CircularBuffer
SwingUtilities.invokeLater( new RunnableOutput( outputArea,
sharedLocation.createStateOutput() ) );
// set up threads
Producer producer1 = new Producer( "T1", sharedLocation, outputArea );
Producer producer2 = new Producer( "T2",sharedLocation, outputArea );
Producer producer3 = new Producer( "T3",sharedLocation, outputArea );
Producer producer4 = new Producer( "T4",sharedLocation, outputArea );
Producer producer5 = new Producer( "T5",sharedLocation, outputArea );
Consumer consumer1 = new Consumer( "T6",sharedLocation, outputArea );
Consumer consumer2 = new Consumer( "T7",sharedLocation, outputArea );
Consumer consumer3 = new Consumer( "T8",sharedLocation, outputArea );
Consumer consumer4 = new Consumer( "T9",sharedLocation, outputArea );
Consumer consumer5 = new Consumer( "T10",sharedLocation, outputArea );
producer1.start(); // start producer1 thread
producer2.start(); // start producer2 thread
producer3.start(); // start producer3 thread
producer4.start(); // start producer4 thread
producer5.start(); // start producer5 thread
consumer1.start(); // start consumer1 thread
consumer2.start(); // start consumer2 thread
consumer3.start(); // start consumer3 thread
consumer4.start(); // start consumer4 thread
consumer5.start(); // start consume5r thread
} // end constructor
public static void main ( String args[] )
JavaSystem application = new JavaSystem();
application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
} //end main method
} // end class CirclularBufferTest

Answer 1

Sorry for the ugly code, I try to post it again.
public interface Buffer {
public void set( int value ); // place value into Buffer
public int get(); // return value from Buffer
import javax.swing.*;
public class CircularBuffer implements Buffer {
// each array element is a buffer
private int buffers[] = { -1, -1, -1 };
// occupiedBufferCount maintains count of occupied buffers
public int occupiedBufferCount = 0;
// variables that maintain read and write buffer locations
private int readLocation = 0, writeLocation = 0;
// reference to GUI component that displays output
private JTextArea outputArea;
// constructor
public CircularBuffer( JTextArea output )
outputArea = output;
} //end CircularBuffer
// place value into buffer
public synchronized void set( int value )
// for output purposes, get name of thread that called this method
String name = Thread.currentThread().getName();
// while there are no empty locations, place thread in waiting state
while ( occupiedBufferCount == buffers.length ) {
// output thread information and buffer information, then wait
try {
SwingUtilities.invokeLater( new RunnableOutput( outputArea,
"\nAll buffers full. " + name + " waits." ) );
wait();
} //end try
// if waiting thread interrupted, print stack trace
catch ( InterruptedException exception )
exception.printStackTrace();
} //end catch
} // end while
// place value in writeLocation of buffers
buffers[ writeLocation ] = value;
// update Swing GUI component with produced value
SwingUtilities.invokeLater( new RunnableOutput( outputArea,
"\n" + name + " writes " + buffers[ writeLocation ] + " ") );
// just produced a value, so increment number of occupied buffers
++occupiedBufferCount;
// update writeLocation for future write operation
writeLocation = ( writeLocation + 1 ) % buffers.length;
// display contents of shared buffers
SwingUtilities.invokeLater( new RunnableOutput(
outputArea, createStateOutput() ) );
notify(); // return waiting thread (if there is one) to ready state
} // end method set
// return value from buffer
public synchronized int get()
// for output purposes, get name of thread that called this method
String name = Thread.currentThread().getName();
// while no data to read, place thread in waiting state
while ( occupiedBufferCount == 0 ) {
// output thread information and buffer information, then wait
try {
SwingUtilities.invokeLater( new RunnableOutput( outputArea,
"\nAll buffers empty. " + name + " waits.") );
wait();
} //end try
// if waiting thread interrupted, print stack trace
catch ( InterruptedException exception ) {
exception.printStackTrace();
} //end catch
} // end while
// obtain value at current readLocation
int readValue = buffers[ readLocation ];
// update Swing GUI component with consumed value
SwingUtilities.invokeLater( new RunnableOutput( outputArea,
"\n" + name + " reads " + readValue + " ") );
// just consumed a value, so decrement number of occupied buffers
--occupiedBufferCount;
// update readLocation for future read operation
readLocation = ( readLocation + 1 ) % buffers.length;
// display contents of shared buffers
SwingUtilities.invokeLater( new RunnableOutput(
outputArea, createStateOutput() ) );
notifyAll(); // return all waiting thread to ready state
return readValue;
} // end method get
// create state output
public String createStateOutput()
// first line of state information
String output =
"(buffers occupied: " + occupiedBufferCount + ")\nbuffers: ";
for ( int i = 0; i < buffers.length; i++ )
output += " " + buffers[ i ] + " ";
// second line of state information
output += "\n ";
for ( int i = 0; i < buffers.length; i++ )
output += "---- ";
// third line of state information
output += "\n ";
// append readLocation (R) and writeLocation (W)
// indicators below appropriate buffer locations
for ( int i = 0; i < buffers.length; i++ )
if ( i == writeLocation && writeLocation == readLocation )
output += " WR ";
else if ( i == writeLocation )
output += " W ";
else if ( i == readLocation )
output += " R ";
else
output += " ";
output += "\n";
return output;
} // end method createStateOutput
} // end class CircularBuffer
import javax.swing.*;
public class RunnableOutput implements Runnable {
private JTextArea outputArea;
private String messageToAppend;
// initialize outputArea and message
public RunnableOutput( JTextArea output, String message )
outputArea = output;
messageToAppend = message;
} //end RunableOutput
// method called by SwingUtilities.invokeLater to update outputArea
public void run()
outputArea.append( messageToAppend );
} // end run
} // end class RunnableOutput
import javax.swing.*;
public class Producer extends Thread {
private CircularBuffer sharedLocation;
private JTextArea outputArea;
// constructor
public Producer(String name, CircularBuffer shared, JTextArea output)
super( name );
sharedLocation = shared;
outputArea = output;
} //end contructor
// store values in sharedLocation's buffer
public void run()
while(sharedLocation.occupiedBufferCount>=0){
// sleep 0 to 10 seconds, then place integer value 0 to 99 in Buffer
int value = ( int )(Math.random() * 99) ;
try {
Thread.sleep( ( int ) ( Math.random() * 10001 ) );
sharedLocation.set( value );
} //end try
// if sleeping thread interrupted, print stack trace
catch ( InterruptedException exception ) {
exception.printStackTrace();
} //end catch
} // end while
} // end method run
} // end class Producer
import javax.swing.*;
public class Consumer extends Thread {
private CircularBuffer sharedLocation; // reference to shared object
private JTextArea outputArea;
// constructor
public Consumer(String name, CircularBuffer shared, JTextArea output)
super( name );
sharedLocation = shared;
outputArea = output;
}// end constructor
// read sharedLocation's value two times and sum the values
public void run()
int sum = 0;
String name = getName();
while(sharedLocation.occupiedBufferCount>=0){
// read value from Buffer and add to sum
try {
int num1 = sharedLocation.get();
int num2 = sharedLocation.get();
sum = num1 + num2;
System.out.println(name + " Sum = " + sum);
} //end try
// if Exception, print stack trace
catch ( Exception exception ) {
exception.printStackTrace();
} //end catch
SwingUtilities.invokeLater( new RunnableOutput( outputArea,
"\nTotal " + name + " consumed: " + sum + ".\n"
} // end while
} // end method run
} // end class Consumer
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
// set up the producer and consumer threads and start them
public class JavaSystem extends JFrame {
JTextArea outputArea;
// set up GUI
public JavaSystem()
super( "TMA2 Q3" );
outputArea = new JTextArea( 20,30 );
outputArea.setFont( new Font( "Monospaced", Font.PLAIN, 12 ) );
getContentPane().add( new JScrollPane( outputArea ) );
setSize( 310, 500 );
setVisible( true );
// create shared object used by threads; we use a CircularBuffer reference
CircularBuffer sharedLocation = new CircularBuffer( outputArea );
// display initial state of buffers in CircularBuffer
SwingUtilities.invokeLater( new RunnableOutput( outputArea,
sharedLocation.createStateOutput() ) );
// set up threads
Producer producer1 = new Producer( "T1", sharedLocation, outputArea );
Producer producer2 = new Producer( "T2",sharedLocation, outputArea );
Producer producer3 = new Producer( "T3",sharedLocation, outputArea );
Producer producer4 = new Producer( "T4",sharedLocation, outputArea );
Producer producer5 = new Producer( "T5",sharedLocation, outputArea );
Consumer consumer1 = new Consumer( "T6",sharedLocation, outputArea );
Consumer consumer2 = new Consumer( "T7",sharedLocation, outputArea );
Consumer consumer3 = new Consumer( "T8",sharedLocation, outputArea );
Consumer consumer4 = new Consumer( "T9",sharedLocation, outputArea );
Consumer consumer5 = new Consumer( "T10",sharedLocation, outputArea );
producer1.start(); // start producer1 thread
producer2.start(); // start producer2 thread
producer3.start(); // start producer3 thread
producer4.start(); // start producer4 thread
producer5.start(); // start producer5 thread
consumer1.start(); // start consumer1 thread
consumer2.start(); // start consumer2 thread
consumer3.start(); // start consumer3 thread
consumer4.start(); // start consumer4 thread
consumer5.start(); // start consume5r thread
} // end constructor
public static void main ( String args[] )
JavaSystem application = new JavaSystem();
application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
} //end main method
} // end class CirclularBufferTest