Java ConcurrentHashMap （Java代码实战-005）详解编程语言

package Threads; 
 
import com.google.common.collect.Maps; 
 
import java.util.concurrent.ConcurrentMap; 
import java.util.concurrent.ExecutorService; 
import java.util.concurrent.Executors; 
 
/** 
 * Created by xfyou 2018/5/21 16:55. 
 * 一个采用ConcurrentHashMap并发写数据的例子 
 */ 
public class ConcurrentHashMapDemo { 
    private final ConcurrentMap<Integer, String> conHashMap = Maps.newConcurrentMap(); 
 
    public static void main(String[] args) { 
        ExecutorService service = Executors.newFixedThreadPool(3); 
        try { 
            ConcurrentHashMapDemo ob = new ConcurrentHashMapDemo(); 
            service.execute(ob.new WriteThreadOne()); 
            service.execute(ob.new WriteThreadTwo()); 
            service.execute(ob.new ReadThread()); 
        } finally { 
            service.shutdown(); 
        } 
    } 
 
    /** 
     * 线程A向Map中put数据 
     */ 
    class WriteThreadOne implements Runnable { 
 
        @Override 
        public void run() { 
            for (int i = 0; i < 10; i++) { 
                conHashMap.putIfAbsent(i, "A" + i); 
            } 
        } 
    } 
 
    /** 
     * 线程B向Map中put数据 
     */ 
    class WriteThreadTwo implements Runnable { 
 
        @Override 
        public void run() { 
            for (int i = 0; i < 5; i++) { 
                conHashMap.putIfAbsent(i, "B" + i); 
            } 
        } 
    } 
 
    /** 
     * 线程C读取Map中的数据 
     */ 
    class ReadThread implements Runnable { 
 
        @Override 
        public void run() { 
            for (Integer k : conHashMap.keySet()) { 
                System.out.println(k + ":" + conHashMap.get(k)); 
            } 
        } 
    } 
}