Use of Java concurrency Programming _wait and notify (iii)

Package Sync;import Java.util.arraylist;import Java.util.list;public class Waitandnotify {private volatile static List list= new ArrayList ();p rivate void Add () {list.add ("Wang"); private int size () {return list.size ();} public static void Main (string[] args) {final waitandnotify list1 = new Waitandnotify ();/* * 1. Instantiate an object as a lock, below T1 and T2 competition This lock is implemented in sync * 2. There is a wait, notify method under object (interview often asks: What are the methods under Object) * 3. Note that each object has both methods and can be treated as a lock */final object lock = new Object (); Thread t1 = new Thread (new Runnable () {@Overridepublic void run () {try {synchronized (lock) {for (int i = 0; i <; i++ ) {List1.add (); System.out.println ("Current thread:" + thread.currentthread (). GetName () + "added an element"); Thread.Sleep (+), if (list1.size () = = 5) {System.out.println ("notification has been issued:"); /notify does not release the lock, the for loop will continue to execute lock.notify ();}}} catch (Interruptedexception e) {e.printstacktrace ();}}}, "T1"); Thread t2 = new Thread (new Runnable () {@Overridepublic void run () {synchronized (lock) {/* * * If the T2 thread is executed first, if size is not 5, wait * WA It releases the lock */if (list1.size ()! = 5) {try {System.out.println ("T2 Enter:"); Thread.Sleep (+); lock.wait ();} catch (Interruptedexception e) {e.printstacktrace ();}} System.out.println ("Current thread received notification:" + thread.currentthread (). GetName () + "List size = 5, thread stop"); throw new RuntimeException ( }}}, "T2"); T2.start (); T1.start ();}}

Output Result:

T2 Enter: Current thread: T1 adds an element to the current thread: T1 adds an element to the current thread: T1 adds an element to the current thread: T1 adds an element to the current thread: T1 added an element has been notified. Current thread: T1 adds an element to the current thread: T1 adds an element to the current thread: T1 adds an element to the current thread: T1 adds an element to the current thread: T1 added an element the current thread receives notification: t2list size = 5, thread stop exception in Thread "T2" Java.lang.RuntimeExceptionat sync. Waitandnotify$2.run (waitandnotify.java:73) at Java.lang.Thread.run (Unknown Source)

　　

Code interpretation:

The first step: Execute T2 thread, enter the Run method, list.size not equal to 5, lock.wait release lock, T2 process Wait, turn to execute T1

Second step: Execute T1 process, get lock, execute for Loop, notify when list.size equals 5 o'clock. Wakes the T2 process, but continues execution of the For loop because the notify does not release the lock

Step three: T2 process is awakened, so list.size already equals 10, not equal to 5, directly outputs the last two lines of code

Use of Java concurrency Programming _wait and notify (iii)