Use AtomicLong to generate ID : AtomicLong « JDK 7 « Java

1. Java
2. JDK 7
3. AtomicLong

Use AtomicLong to generate ID

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.concurrent.atomic.AtomicLong;

public class Test {

  public static void main(String[] args) {
    final AtomicLong orderIdGenerator = new AtomicLong(0);
    final List<Item> orders = Collections
        .synchronizedList(new ArrayList<Item>());

    for (int i = 0; i < 10; i++) {
      Thread orderCreationThread = new Thread(new Runnable() {
        public void run() {
          for (int i = 0; i < 10; i++) {
            long orderId = orderIdGenerator.incrementAndGet();
            Item order = new Item(Thread.currentThread().getName(), orderId);
            orders.add(order);
          }
        }
      });
      orderCreationThread.setName("Order Creation Thread " + i);
      orderCreationThread.start();
    }
    try {
      Thread.sleep(1000);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
    Set<Long> orderIds = new HashSet<Long>();
    for (Item order : orders) {
      orderIds.add(order.getID());
      System.out.println("Order id:" + order.getID());
    }
  }
}

class Item {
  String itemName;
  long id;

  Item(String n, long id) {
    this.itemName = n;
    this.id = id;
  }

  public String getItemName() {
    return itemName;
  }

  public long getID() {
    return id;
  }
}

 

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