1. //Java implementation of a producer and consumer
2. //that use semaphores to control synchronization
3. import java.util.concurrent.Semaphore;
4. class Queue {
5. // an item
6. int item;
7. // semCon initialized with 0 permits
8. // to ensure put() executes first
9. static Semaphore semCon = new Semaphore(0);
10. static Semaphore semProd = new Semaphore(1);
11.  
12. //to get an item from buffer
13. void get() {
14. try {
15. // Before consumer can consume an item,
16. // it must acquire a permit from semCon
17. semCon.acquire();
18. }
19. catch(InterruptedException e) {
20. System.out.println("InterruptedException caught");
21. }
22.  
23. //consumer consuming an item
24. System.out.println("Consumer consumed item : " + item);
25. // After consumer consumes the item,
26. // it releases semProd to notify producer
27. semProd.release();
28. }
29.  
30. //to put an item in buffer
31. void put(int item) {
32. try {
33. // Before producer can produce an item,
34. // it must acquire a permit from semProd
35. semProd.acquire();
36. } catch(InterruptedException e) {
37. System.out.println("InterruptedException caught");
38. }
39. //producer producing an item
40. this.item = item;
41. System.out.println("Producer produced item : " + item);
42. // After producer produces the item,
43. // it releases semCon to notify consumer
44. semCon.release();
45. }
46. }