Java - 为什么锁在多线程 java 程序中对我的变量不起作用？

Question

I am trying to learn concurrency in Java and not getting the desired results, why arent my locks working? I have tried every tutorial I can find and it is getting me closer, but not 100%

import java.util.concurrent.locks.*;
public class Concurrent extends Thread {
  private Object lock1;// = new Object();
  // static means the variable is shared by all objects, i.e. global
  static long counter = 0;
  static long threads = 10;
  static long count_each = 1000000;
  //private Object lock1 = new Object();
  private Object lock2 = new Object();
  ReentrantLock lock = new ReentrantLock();

  public synchronized void run() //Helps ++
  //public void run() 
  {    
    //synchronized (lock1) 
    //{
        //lock.lock();
        //Object lock1 = new Object();
        long count = count_each;   // local variable for this thread only
        while (count-- > 0) 
        {   
            //lock.lock();
            //try 
            //{
            Object lock1 = new Object();
            synchronized (lock1)  //Helps ++
            {
                counter++;
            }
            //}
            //finally 
            //{
            //    lock.unlock();
            //}
        }
        //lock.unlock();
    //}

  }

Previous attempts are commented out, I have tried just about every combination of everythnig you see.

Answer 1

Your locks are not static , so every thread uses its own lock what renderes them useless.

Answer 2

If you want concurrency, get rid of locks and synchronize and use AtomicLong instead of long counter (if you just want incrementing operation). In your case although you are using threads, your logic executes sequentially.