Multithreaded Programming

1
Multithreaded Programming

• Chapter 11

2
Multithreading

• Allows different sections of code to run at the
  same time (seem to run at the same time)
• Parallel processors
• OS
• Allows the programmer use the CPU when other
  tasks have to wait for some type of input
• Keyword (synchronize)
• Locks other threads from accessing methods

3
Thread Class and Runnable Interface

• Methods
• getName
• getPriority
• isAlive
• join
• run // method that must be implemented
• sleep // allows other threads access to the CPU
• start // in parent class that calls the run method

4
Thread Class and Runnable Interface

• Creating a thread
• Implement the Runnable interface
• Extend the Thread class
• public void run( )
• //handles the items for the thread
• Called when we call start( )

5
An Example of implementing the interface Runnable

• class Test implements Runnable
• Thread t
• public Test( )
• t new Thread(this, anyName)
• t.start( ) // starting thread which will call
  run
• public void run ( )
• try
• // implement what should be done in this class
  within the thread
• t.sleep(200) // release CPU for time (in
  milliseconds)
• catch (InterruptedException ie)

6
An Example ofextending the Thread Class

• class Test extends Thread
• public Test( )
• super( anyName)
• start( ) // starting thread which will call
  run
• public void run ( )
• try
• // implement what should be done in this class
  within the thread
• this.sleep(200) // release CPU for time (in
  milliseconds)
• catch (InterruptedException ie)

7
Creating Multiple Threads

• Call objects several times
• In main the threads execute on their own
• In the applet youll need to have the applets
  thread give control to the other threads by
  making it a thread as well.

8
Other Information about Threads

• Thread priorities
• setPriority( )
• MIN_PRIORITY, MAX_PRIORITY, NORM_PRIORITY
• Synchronization
• synchronized void call (String msg)
• Makes sure that only one thread is allowed
  through the method at a time
• Or synchronized block of code
• Interthread Communication
• wait ( ), notify ( ), notifyAll( )
• Deadlock