Thread không có Synchronization
class PrintDemo { public void printCount(){ try { for(int i = 5; i > 0; i--) { System.out.println("Counter --- " + i ); } } catch (Exception e) { System.out.println("Thread interrupted."); } } } class ThreadDemo extends Thread { private Thread t; private String threadName; PrintDemo PD; ThreadDemo( String name, PrintDemo pd){ threadName = name; PD = pd; } public void run() { PD.printCount(); System.out.println("Thread " + threadName + " exiting."); } public void start () { System.out.println("Starting " + threadName ); if (t == null) { t = new Thread (this, threadName); t.start (); } } } public class TestThread { public static void main(String args[]) { PrintDemo PD = new PrintDemo(); ThreadDemo T1 = new ThreadDemo( "Thread - 1 ", PD ); ThreadDemo T2 = new ThreadDemo( "Thread - 2 ", PD ); T1.start(); T2.start(); // wait for threads to end try { T1.join(); T2.join(); } catch( Exception e) { System.out.println("Interrupted"); } } }
Nó sẽ cho kết quả khác nhau mỗi lần chúng ta chạy chương trình này:
Starting Thread - 1 Starting Thread - 2 Counter --- 5 Counter --- 4 Counter --- 3 Counter --- 5 Counter --- 2 Counter --- 1 Counter --- 4 Thread Thread - 1 exiting. Counter --- 3 Counter --- 2 Counter --- 1 Thread Thread - 2 exiting.Thread có Synchronization
class PrintDemo { public void printCount(){ try { for(int i = 5; i > 0; i--) { System.out.println("Counter --- " + i ); } } catch (Exception e) { System.out.println("Thread interrupted."); } } } class ThreadDemo extends Thread { private Thread t; private String threadName; PrintDemo PD; ThreadDemo( String name, PrintDemo pd){ threadName = name; PD = pd; } public void run() { synchronized(PD) { //Cách viết phương thức đồng bộ hóa PD.printCount(); } System.out.println("Thread " + threadName + " exiting."); } public void start () { System.out.println("Starting " + threadName ); if (t == null) { t = new Thread (this, threadName); t.start (); } } } public class TestThread { public static void main(String args[]) { PrintDemo PD = new PrintDemo(); ThreadDemo T1 = new ThreadDemo( "Thread - 1 ", PD ); ThreadDemo T2 = new ThreadDemo( "Thread - 2 ", PD ); T1.start(); T2.start(); // wait for threads to end try { T1.join(); T2.join(); } catch( Exception e) { System.out.println("Interrupted"); } } }
Nó sẽ cho cùng một kết quả mỗi khi chạy chương trình này:
Starting Thread - 1 Starting Thread - 2 Counter --- 5 Counter --- 4 Counter --- 3 Counter --- 2 Counter --- 1 Thread Thread - 1 exiting. Counter --- 5 Counter --- 4 Counter --- 3 Counter --- 2 Counter --- 1 Thread Thread - 2 exiting.
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