Java Coding Problems

210. Exchanger

An exchanger is a Java synchronizer that allows two threads to exchange objects at an exchange or synchronization point.

Mainly, this kind of synchronizer acts as a barrier. Two threads wait for each other at a barrier. They exchange an object and continue their usual tasks when both arrive.

The following diagram depicts in four steps the flow of an exchanger:

In API terms, this synchronizer is exposed by java.util.concurrent.Exchanger.

An Exchanger can be created via an empty constructor and exposes two exchange() methods:

• One that gets only the object that it will offer
• One that gets a timeout (before another thread enters ...