2、HashTable: a. 是线程安全的; b. 无论是key还是value都不允许有null值的存在;在HashTable中调用Put方法时,如果key为null,直接抛出NullPointerException异常; c. 遍历使用的是Enumeration列举; 3、HashSet: a. 基于HashMap实现,无容量限制; b. 是非线程安全的; c. 不保证数据的有序; TreeSet、TreeMap: ...
importjava.util.concurrent.ConcurrentHashMap;publicclassSafeConcurrentHashMapExample{publicstaticvoidmain(String[]args){ConcurrentHashMap<Integer,String>concurrentHashMap=newConcurrentHashMap<>();Runnabletask=()->{for(inti=0;i<1000;i++){concurrentHashMap.put(i,"Value "+i);}};Threadt1=newThread(t...
这样就实现了所谓的线程安全。 二、线程安全(Thread-safe)的集合对象: Vector 线程安全: HashTable 线程安全: StringBuffer 线程安全: 三、非线程安全的集合对象: ArrayList : LinkedList: HashMap: HashSet: TreeMap: TreeSet: StringBulider: 四、相关集合对象比较: Vector、ArrayList、LinkedList: 1、Vector: Vec...
Thread-Safe MapThread 2Thread 1Thread-Safe MapThread 2Thread 1 并发访问的旅程 添加元素 Thread 1 ->> ConcurrentHashMap Thread 2 ->> ConcurrentHashMap 读取元素 Thread 1 ->> ConcurrentHashMap Thread 1 ->> Thread 1 Thread 2 ->> Thread 2 多线程访问 Map 的旅程 总结 在多线程环境中选择合适...
set.add(456);//make thread-safe hashmapMap map=Collections.synchronizedMap(newHashMap()); map.put(1, "thb"); map.put(12, "bill tang"); CopyOnWriteArrayList与Collections.synchronizedList的性能对比 http://blog.csdn.net/zljjava/article/details/48139465 ...
struts1.x获取action的方式是单例的,所有的action都被维护在一个hashMap里,当有请求到达时,先根据action的名称去hashMap里查找要请求的Action是否已经存在,如果存在,则直接返回hashMap里的action。如果不存在,则创建一个新的Action实例。这与Servelt是类似的。
推理ConcurrentHashMap的实现1.8 ① JDK的描述 代码语言:javascript 复制 If a thread-safe implementation is not needed,it is recommended to use HashMapinplaceofcode Hashtable.If a thread-safe highly-concurrent implementation is desired,then it is recommended to use ConcurrentHashMapinplaceofcode Hashta...
证明HashMap的非线程安全性 package com.concurrence; import java.util.HashMap; public class ThreadNotSafeHashmap { public static void main(String args[]) throws InterruptedException { final HashMap<String, String> firstHashMap = new HashMap<String, String>(); ...
比如：CopyOnWriteArrayList、ConcurrentHashMap、CopyOnWriteArraySet、ArrayBlockingQueue等等。例如：publicclassHashMapTest {privatestaticConcurrentHashMap<String, Object>hashMap=newConcurrentHashMap<>();publicstaticvoidmain(String[] args) {newThread(newRunnable() {@Overridepublicvoidrun() {hashMap.put("key1",...
3.HashMap的线程不安全解决方案 package test.notsafe;importjava.util.Collections;importjava.util.HashMap;importjava.util.Map;importjava.util.UUID;importjava.util.concurrent.ConcurrentHashMap;/** * 演示HashMap的线程不安全问题及解决方案 */publicclassThreadDemo4{publicstaticvoidmain(String[] args) {/...