Blocking queue example

Threads trying to get elements from an empty blocking queue will be blocked , Until other threads insert new elements into the empty queue . Again · 
Threads trying to add new elements to the full blocking queue will also be blocked , Until other threads remove one or more elements from the column or clear the queue completely, the queue will be idle again and added later  

  Throw an exception : add,remove Method , If the queue is full add, If the queue is empty remove Throw an exception

 public static void main(String[] args) {
        BlockingQueue<String> blockingQueue=new ArrayBlockingQueue<>(3);
        System.out.println(blockingQueue.add("a"));
        System.out.println(blockingQueue.add("b"));
        System.out.println(blockingQueue.add("c"));
        // use add Method if it exceeds the predefined 3 Elements will throw exceptions 
        System.out.println(blockingQueue.add("x"));
    }

// Execution results 
true
true
true
Exception in thread "main" java.lang.IllegalStateException: Queue full
	at java.util.AbstractQueue.add(AbstractQueue.java:98)
	at java.util.concurrent.ArrayBlockingQueue.add(ArrayBlockingQueue.java:312)
	at com.hy.controller.ResController.main(ResController.java:942)

Special values

public static void main(String[] args) {
        BlockingQueue<String> blockingQueue=new ArrayBlockingQueue<>(3);
        System.out.println(blockingQueue.offer("a"));
        System.out.println(blockingQueue.offer("b"));
        System.out.println(blockingQueue.offer("c"));
        // use offer Method if it exceeds the predefined 3 Elements will return false
        System.out.println(blockingQueue.offer("x"));
        // Returns the queue header element 
        System.out.println(blockingQueue.peek());
        // use poll Method   Get the element from the empty blocking queue and return null
        System.out.println(blockingQueue.poll());
        System.out.println(blockingQueue.poll());
        System.out.println(blockingQueue.poll());
        System.out.println(blockingQueue.poll());
    }
    // Execution results      
   true
   true
   true
   false
   a
   a
   b
   c
   null

Blocking :

Overtime :

 public static void main(String[] args) throws InterruptedException {
        BlockingQueue<String> blockingQueue=new ArrayBlockingQueue<>(3);
        System.out.println(blockingQueue.offer("a",2, TimeUnit.SECONDS));
        System.out.println(blockingQueue.offer("b",2, TimeUnit.SECONDS));
        System.out.println(blockingQueue.offer("c",2, TimeUnit.SECONDS));
        // use offer Method if it exceeds the predefined 3 Elements will return false
        System.out.println(" Wait two seconds ===============");
        System.out.println(blockingQueue.offer("x",2, TimeUnit.SECONDS)); 
    }

 // Execution results  
true
true
true
 Wait two seconds ===============
false

 SynchronousQueue:  No capacity . The synchronization queue has no capacity .
And others BlockingQueue Different ,SynchronousQueue It's a... That doesn't store elements BlockingQuege. 
every last put The operation must wait for one take operation , Otherwise, you can't continue to add elements , vice versa . 
Sample code :

  public static void main(String[] args) throws InterruptedException {
        BlockingQueue<String> blockingQueue=new SynchronousQueue<>();
        new Thread(()->{
            try {
                System.out.println(Thread.currentThread().getName()+"\tput 1");
                blockingQueue.put("1");

                System.out.println(Thread.currentThread().getName()+"\tput 2");
                blockingQueue.put("2");

                System.out.println(Thread.currentThread().getName()+"\tput 3");
                blockingQueue.put("3");
              
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        },"t1").start();

        new Thread(()->{
            try {
                Thread.sleep(5);
                System.out.println(Thread.currentThread().getName()+"\t Take out :"+blockingQueue.take());

                Thread.sleep(5);
                System.out.println(Thread.currentThread().getName()+"\t Take out :"+blockingQueue.take());

                Thread.sleep(5);
                System.out.println(Thread.currentThread().getName()+"\t Take out :"+blockingQueue.take());
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

        },"t2").start();
    }

  // Execution results 
t1	put 1
t2	 Take out :1
t1	put 2
t2	 Take out :2
t1	put 3
t2	 Take out :3

topic Objective : A variable with an initial value of zero , Two threads operate on it alternately , One plus 1, One minus 1
Prevent false wake-up mechanism
Sample code :
 

class ShareData{
    private int number=0;
    private Lock lock=new ReentrantLock();
    private Condition condition=lock.newCondition();

    public void increment() {
        lock.lock();
        try {
            //1  Judge    use while no need if , To avoid false awakening 
            while (number!=0){
                //2  wait for , Unable to produce 
                condition.await();
            }
            //2  work 
            number++;
            System.out.println(Thread.currentThread().getName()+"\t"+number);
            //3  Notification wake up 
            condition.signalAll();
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            lock.unlock();
        }
    }
    public void dncrement() {
        lock.lock();
        try {
            //1  Judge 
            while (number==0){
                //2  wait for , Unable to produce 
                condition.await();
            }
            //2  work 
            number--;
            System.out.println(Thread.currentThread().getName()+"\t"+number);
            //3  Notification wake up 
            condition.signalAll();
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            lock.unlock();
        }
    }
}

// Execution results 
aa	1
bb	0
aa	1
bb	0
aa	1
bb	0
aa	1
bb	0
aa	1
bb	0