condition

锁只能互斥，但是不能通信。condition就是解决该问题的，类似于wait()和notify()。

一个condition

package cn.itcast.heima2;

import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class ConditionCommunication {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		
		final Business business = new Business();
		new Thread(
				new Runnable() {
					
					@Override
					public void run() {
					
						for(int i=1;i<=50;i++){
							business.sub(i);
						}
						
					}
				}
		).start();
		
		for(int i=1;i<=50;i++){
			business.main(i);
		}
		
	}

	static class Business {
			Lock lock = new ReentrantLock();
			Condition condition = lock.newCondition();//todo
		  private boolean bShouldSub = true;
		  public  void sub(int i){
			  lock.lock();
			  try{
				  while(!bShouldSub){
					  try {
						condition.await();//todo
					} catch (Exception e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				  }
					for(int j=1;j<=10;j++){
						System.out.println("sub thread sequence of " + j + ",loop of " + i);
					}
				  bShouldSub = false;
				  condition.signal();//todo
			  }finally{
				  lock.unlock();
			  }
		  }
		  
		  public  void main(int i){
			  lock.lock();
			  try{
				 while(bShouldSub){//todo while避免假醒
				  		try {
							condition.await();//todo
						} catch (Exception e) {
							// TODO Auto-generated catch block
							e.printStackTrace();
						}
				  	}
					for(int j=1;j<=100;j++){
						System.out.println("main thread sequence of " + j + ",loop of " + i);
					}
					bShouldSub = true;
					condition.signal();//todo 
		  }finally{
			  lock.unlock();
		  }
	  }
	
	}
}

两个condition

class BoundedBuffer { 
        final Lock lock = new ReentrantLock(); 
        final Condition notEmpty = lock.newCondition(); 
        final Condition notFull = lock.newCondition(); 
 
        final int MAX_SIZE = 5; 
        List<Object> list = new ArrayList<Object>(); 
        int count = 0; 
 
        public void put(Object obj) throws InterruptedException { 
            lock.lock(); 
            try { 
                while (count == MAX_SIZE) { 
                    notFull.await(); 
                } 
                list.add(obj); 
                count++; 
                System.out.println("call: notEmpty.signal()"); 
                notEmpty.signal(); 
            } finally { 
                lock.unlock(); 
            } 
        } 
 
        public Object take() throws InterruptedException { 
            lock.lock(); 
            try { 
                while (count == 0) { 
                    notEmpty.await(); 
                } 
                Object obj = list.remove(0); 
                count --; 
                System.out.println("call: notFull.signal()"); 
                notFull.signal(); 
                return obj; 
            } finally { 
                lock.unlock(); 
            } 
        } 
    }

三个condition

package cn.itcast.heima2;

import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class ThreeConditionCommunication {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		
		final Business business = new Business();
		new Thread(
				new Runnable() {
					
					@Override
					public void run() {
					
						for(int i=1;i<=50;i++){
							business.sub2(i);
						}
						
					}
				}
		).start();
		
		new Thread(
				new Runnable() {
					
					@Override
					public void run() {
					
						for(int i=1;i<=50;i++){
							business.sub3(i);
						}
						
					}
				}
		).start();		
		
		for(int i=1;i<=50;i++){
			business.main(i);
		}
		
	}

	static class Business {
			Lock lock = new ReentrantLock();
			Condition condition1 = lock.newCondition();
			Condition condition2 = lock.newCondition();
			Condition condition3 = lock.newCondition();
		  private int shouldSub = 1;
		  public  void sub2(int i){
			  lock.lock();
			  try{
				  while(shouldSub != 2){
					  try {
						condition2.await();
					} catch (Exception e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				  }
					for(int j=1;j<=10;j++){
						System.out.println("sub2 thread sequence of " + j + ",loop of " + i);
					}
				  shouldSub = 3;
				  condition3.signal();
			  }finally{
				  lock.unlock();
			  }
		  }

		  public  void sub3(int i){
			  lock.lock();
			  try{
				  while(shouldSub != 3){
					  try {
						condition3.await();
					} catch (Exception e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				  }
					for(int j=1;j<=20;j++){
						System.out.println("sub3 thread sequence of " + j + ",loop of " + i);
					}
				  shouldSub = 1;
				  condition1.signal();
			  }finally{
				  lock.unlock();
			  }
		  }		  
		  
		  public  void main(int i){
			  lock.lock();
			  try{
				 while(shouldSub != 1){
				  		try {
							condition1.await();
						} catch (Exception e) {
							// TODO Auto-generated catch block
							e.printStackTrace();
						}
				  	}
					for(int j=1;j<=100;j++){
						System.out.println("main thread sequence of " + j + ",loop of " + i);
					}
					shouldSub = 2;
					condition2.signal();
		  }finally{
			  lock.unlock();
		  }
	  }
	
	}
}