Reeks 2:

Gedistribueerde Plants vs. Zombies

Java Concurrency: Counter example

class Counter {
private int c = 0;
public void increment() {
        c++;
    }
public void decrement() {
        c--;
    }
public int value() {
return c;
    }
}

Two threads using the same counter

     THREAD 1                              THREAD 2

1. retrieve c (0)

                                         2. retrieve c (0)

3. increment c (1)

                                         4. decrement c (-1)

5. save c (1)

                                         6. save c (-1)

Synchronized Methods

• public synchronized void increment () { .. }
  
  
• No interleaving
  
  
• Changes to the state of the object are visible to all threads
  

Java Threads

    public class MyRunnable implements Runnable {

       public void run() {

           // code to run in thread

        }

     };
     (new Thread(new MyRunnable())).start(); 

    public class MyThread extends Thread {

         public void run() {

             // code to run in thread

         }

    };
    new MyThread().start(); 

Plants vs. Zombies

Streams

InputStream in = socket.getInputStream();

while(true) {

     if (in.available() >= 4 {

         int first = in.read();

         int second = in.read();

                   .

                   .

                   .