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Atomic系列类封装了一系列的基础类型和对象操作，其主要目的就是为了实现原子性，主要核心类如下：

AtomicInteger

AtomicLong

AtomicBoolean

AtomicIntegerArray

AtomicLongArray

AtomicReference

原子性，多线程中能并发操作，保证数据准确

AtomicInteger与synchronized（将add操作变成一个原子操作）能保证原子性操作，（最终结果1000）能保证方法内运行中不会出现617，613之类的数据

package com.bfxy.thread.core.cas;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

public class UseAtomic {

	private static /* int count = 0; */ AtomicInteger  count = new AtomicInteger(0);
	
	public synchronized int add(){
		//return count.addAndGet(10);
		count.addAndGet(3);  // + 3
		count.addAndGet(4);  // + 4
		count.addAndGet(2);  // + 2 
		count.addAndGet(1);  // + 1
		
		
		// 写了一段代码逻辑........ count.add(1);
		
		// 又写了一个复杂的逻辑...
		// count.add(1);
		// = 2
		
		return count.get();	
	}
	
	public static void main(String[] args) {
		UseAtomic ua = new UseAtomic();
		
		List<Thread> list = new ArrayList<>();
		
		//如果使用atomicIntger 最终的结果 一定是: 1000
		for(int i =0; i < 100; i++) {
			list.add(new Thread(new Runnable() {
				@Override
				public void run() {
					System.err.println("累计结果:" + ua.add());
				}
			}));
		}
		
		for(Thread t : list) {
			t.start();
		}
		
		
	}
	
	
}

AtomicReference引用对象

package com.bfxy.thread.core.cas;

public class Person {
	private String name;
	private int age;
	
	public Person(String name, int age) {
		super();
		this.name = name;
		this.age = age;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
    public String toString() {
        return "[name: " + this.name + ", age: " + this.age + "]";
    }
}

测试：

package com.bfxy.thread.core.cas;

public class UseAtomicReference1 {

	private static Person person;
	
	public static void main(String[] args) throws InterruptedException {
	    person = new Person("Tom", 18);

	    System.out.println("Person is " + person.toString());

	    Thread t1 = new Thread(new Task1());
	    Thread t2 = new Thread(new Task2());

	    t1.start();
	    t2.start();
	    t1.join();
	    t2.join();
	    
	    Thread.sleep(100);
	    System.out.println("Now Person is " + person.toString());
	}

	static class Task1 implements Runnable {
	    public void run() {
	        person.setAge(19);
	        person.setName("Tom1");

	        System.out.println("Thread1 Values "
	                + person.toString());
	    }
	}

	static class Task2 implements Runnable {
	    public void run() {
	        person.setAge(20);
	        person.setName("Tom2");

	        System.out.println("Thread2 Values "
	                + person.toString());
	    }
	}
}

测试2：

package com.bfxy.thread.core.cas;

import java.util.concurrent.atomic.AtomicReference;

public class UseAtomicReference2 {
	// 普通引用
	private static Person person;
	// 原子性引用
	private static AtomicReference<Person> aRperson;

	public static void main(String[] args) throws InterruptedException {
	    person = new Person("Tom", 18);
	    aRperson = new AtomicReference<Person>(person);

	    System.out.println("Atomic Person is " + aRperson.get().toString());

	    Thread t1 = new Thread(new Task1());
	    Thread t2 = new Thread(new Task2());

	    t1.start();
	    t2.start();
	    t1.join();
	    t2.join();
	    
	    Thread.sleep(500);
	    System.out.println("Now Atomic Person is " + aRperson.get().toString());
	}

	static class Task1 implements Runnable {  
	    public void run() {
	    	System.err.println("ret = " + 
	    				// C A S 原子操作
	    				aRperson.compareAndSet(  //10ms 
	    					aRperson.get(), 
	    					new Person("Tom", aRperson.get().getAge() + 1)
	    			));
	        System.out.println("Thread1 Atomic References "
	                + aRperson.get().toString());
	    }
	}

	static class Task2 implements Runnable {
	    public void run() {
	    	System.err.println("ret = " + 
	    			aRperson.compareAndSet(		//8ms
	    					aRperson.get(), 
	    					new Person("Tom", aRperson.get().getAge() + 2)
	    			));
	        System.out.println("Thread2 Atomic References "
	                + aRperson.get().toString());
	    }
	}
}