Test.java

package com.freemindcafe.concurrency.sample5;

import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.Semaphore;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.function.Consumer;

public class Test {
    
    @org.junit.Test
    public void test_with_out_coordination() throws Exception{
        //Semaphore mutex = new Semaphore(1);
        List<Integer> firstTenInts = new CopyOnWriteArrayList<>();
        
        Runnable r1 = () -> {
            for(int i=0; i <=4; i++){
                firstTenInts.add(2*i+1);
            }
        };
        
        Runnable r2 = () -> {
            for(int i=1; i <=5; i++){
                firstTenInts.add(2*i);
            }
        };
        
        Thread t1 = new Thread(r1);
        Thread t2 = new Thread(r2);
        
        t1.start();
        t2.start();
        
        t1.join();
        t2.join();
        
        System.out.println(firstTenInts);
        
        
    }
    
    @org.junit.Test
    public void test_with_coordination_using_semaphore() throws Exception{
        Semaphore firstOneDone = new Semaphore(0);
        Semaphore secondOneDone = new Semaphore(0);
        List<Integer> firstTenInts = new CopyOnWriteArrayList<>();
        
        Runnable r1 = () -> {
            try{
                for(int i=0; i <=4; i++){
                    //System.out.println("first");
                    firstTenInts.add(2*i+1);
                    firstOneDone.release();
                    secondOneDone.acquire();
                }               
            }
            catch(Exception ex){
                throw new RuntimeException(ex);
            }
        };      
        
        Runnable r2 = () -> {
            try{
                for(int i=1; i <=5; i++){
                    //System.out.println("second");
                    firstOneDone.acquire();
                    firstTenInts.add(2*i);
                    secondOneDone.release();
                }               
            }
            catch(Exception ex){
                throw new RuntimeException(ex);
            }
        };
        
        Thread t1 = new Thread(r1);
        Thread t2 = new Thread(r2);
        
        t1.start();
        t2.start();
        
        t1.join();
        t2.join();
        
        System.out.println(firstTenInts);
        
        
    }
    
    //[FIXME] Can we write is using condition vatiables
    @org.junit.Test
    public void test_with_coordination_using_condition() throws Exception{
        Lock lock = new ReentrantLock();
        Condition firstOneDone = lock.newCondition();
        Condition secondOneDone = lock.newCondition();
        List<Integer> firstTenInts = new CopyOnWriteArrayList<>();
        
        Runnable r1 = () -> {
            try{
                for(int i=0; i <=4; i++){
                    //System.out.println("first");
                    firstTenInts.add(2*i+1);
                    firstOneDone.signal();
                    secondOneDone.wait();
                }               
            }
            catch(Exception ex){
                throw new RuntimeException(ex);
            }
        };      
        
        Runnable r2 = () -> {
            try{
                for(int i=1; i <=5; i++){
                    //System.out.println("second");
                    firstOneDone.wait();
                    firstTenInts.add(2*i);
                    secondOneDone.signal();
                }               
            }
            catch(Exception ex){
                throw new RuntimeException(ex);
            }
        };
        
        Thread t1 = new Thread(r1);
        Thread t2 = new Thread(r2);
        
        t1.start();
        t2.start();
        
        t1.join();
        t2.join();
        
        System.out.println(firstTenInts);
        
        
    } <T> Block<T> exceptionWrappingBlock(Block<T> b) {
         return () -> {
             try { b.accept(); }
             catch (Exception ex) { throw new RuntimeException(ex); }
         };
    }

}

interface Block<T>{
    void accept() throws Exception;
}