Java multithreading: thread synchronization-Experiment 5

original address:
http://blog.csdn.net/huang_xw/article/details/7318554

/*** @ Description: the instance of the stringbuffer object accessed by thread 1. When thread 2 wants to access this object, blocking will occur. * @ author Snoopy * @ blog http://blog.csdn.net/huang_xw */package basic. B _syn; import Org. apache. log4j. logger; public class testsyne {Private Static logger = logger. getlogger (testsyne. class); stringbuffer sb = new stringbuffer ("Initial string +"); // thread 1 static class T1 implements runnable {testsyne s; Public T1 (testsyne sameobj) {This. S = sameobj;} // thread 1 access method syn1 () Public void run () {logger. debug ("Starting thread 1 ........... "); S. syn1 (); logger. debug ("Exit thread 1 ........... ") ;}} // thread 2 static class T2 implements runnable {testsyne s; Public T2 (testsyne sameobj) {This. S = sameobj;} // thread 2 access method syn2 () Public void run () {logger. debug ("start thread 2 ........... "); S. syn2 (); logger. debug ("Exit thread 2 ........... ") ;}} public void syn1 () {string threadstr = thread. currentthread (). getname (); logger. debug ("▲▲▲▲▲▲" + threadstr + "Start access method syn1 ()"); try {synchronized (SB) {logger. debug (threadstr + "accessing object Sb"); sb. append ("string added by thread 1 +"); // simulate a time-consuming process thread with sleep. sleep (5000); logger. debug (threadstr + "sleep ends"); logger. debug ("the string is:" + sb. tostring () ;}} catch (interruptedexception e) {e. printstacktrace ();} logger. debug ("▲▲▲▲▲▲" + threadstr + "Exit method syn1 ()");} public void syn2 () {string threadstr = thread. currentthread (). getname (); logger. debug ("●●●●●●●" + threadstr + "Start access method syn2 ()"); sb. append ("string added by thread 2 +"); logger. debug ("the string is:" + sb. tostring (); logger. debug ("●●●●●●●" + threadstr + "Exit method syn2 ()");} public static void main (string [] ARGs) {// This is the same object to be accessed by multiple threads testsyne sameobj = new testsyne (); // thread 1 access synchronization method syn1 (), thread 2 also accesses the synchronization method syn2 (). thread T1 = new thread (New T1 (sameobj), "thread 1"); thread t2 = new thread (New T2 (sameobj), "thread 2"); t1.start (); // sleep is to ensure that thread 1 starts to run, and first accesses the stringbuffer instance. try {thread. sleep (50);} catch (interruptedexception e) {e. printstacktrace () ;}t2.start ();}}

Execution result:

 
0 [thread 1] Debug basic. B _syn.testsyne-start thread 1 ........... 0 [thread 1] Debug basic. B _syn.testsyne-▲▲▲▲▲method for accessing thread 1 syn1 () 0 [thread 1] Debug basic. B _syn.testsyne-thread 1 is accessing the object sb49 [thread 2] Debug basic. B _syn.testsyne-start thread 2 ........... 49 [thread 2] Debug basic. B _syn.testsyne-●●●●●●● thread 2 start to access method syn2 () 5000 [thread 1] Debug basic. B _syn.testsyne-thread 1 sleep ends 5001 [thread 1] Debug basic. B _syn.testsyne-at this time, the string is: initial string + String added to thread 1 + 5001 [thread 1] Debug basic. B _syn.testsyne-▲▲▲▲▲method of thread 1 exit syn1 () 5001 [thread 2] Debug basic. B _syn.testsyne-the character string is: initial string + String added to thread 1 + String added to thread 2 + 5001 [thread 1] Debug basic. B _syn.testsyne-exit thread 1 ........... 5001 [thread 2] Debug basic. B _syn.testsyne-●●●●●●● thread 2 exit method syn2 () 5001 [thread 2] Debug basic. B _syn.testsyne-exit thread 2 ...........