Java Multithreading--Countdownlatch latching

Countdownlatch a synchronous helper class that allows one or more threads to wait until a set of operations that are executing in another thread is completed.
Latching can delay the progress of a thread until it reaches the terminating state, and latching can be used to ensure that certain activities continue until other activities are completed:

1. Ensure that a calculation does not continue until all the resources it needs are initialized;
2. Ensure that a service is started after all other services it relies on have been started;
3. Wait until all participants in an operation are ready before proceeding.

 PackageCom.company;ImportJava.util.concurrent.CountDownLatch;/** Countdownlatch: Latching, in the completion of certain operations, only the operation of all other threads is complete, the current operation continues to execute*/ Public classTestcountdownlatch { Public Static voidMain (string[] args) {FinalCountdownlatch latch =NewCountdownlatch (50); Latchdemo LD=NewLatchdemo (latch); LongStart =System.currenttimemillis ();  for(inti = 0; I < 50; i++) {            NewThread (LD). Start (); }        Try{latch.await (); } Catch(Interruptedexception e) {}LongEnd =System.currenttimemillis (); System.out.println ("Time-consuming:" + (End-start)); }}classLatchdemoImplementsRunnable {PrivateCountdownlatch latch;  PublicLatchdemo (Countdownlatch latch) { This. Latch =latch; } @Override Public voidrun () {Try {             for(inti = 0; I < 50000; i++) {                if(i% 2 = = 0) {System.out.println (i); }            }        } finally{latch.countdown (); }    }}

Results:

A bit longer to intercept the second half of the paragraph bar:

499944999649998 Time-consuming:7301

Java Multithreading--Countdownlatch latching