系列六、多线程集合不安全

一、多线程List集合不安全

1.1、List集合不安全案例代码

/*** @Author : 一叶浮萍归大海* @Date: 2023/11/20 12:38* @Description: 多线层环境下List集合不安全案例代码*/
public class NotSafeListMainApp {public static void main(String[] args) {List<String> list = new ArrayList<>();for (int i = 1; i <= 30; i++) {new Thread(() -> {list.add(UUID.randomUUID().toString().toLowerCase().substring(0, 8).replaceAll("-", ""));System.out.println("【当前线程】：" + Thread.currentThread().getName() + "，【当前list】：" + list);}, String.valueOf(i)).start();}}}

1.2、解决方法

/*** @Author : 一叶浮萍归大海* @Date: 2023/11/20 12:38* @Description: 多线层环境下List集合不安全解决案例代码*/
public class NotSafeListPlusMainApp {public static void main(String[] args) {// List<String> list = Collections.synchronizedList(new ArrayList<>());List<String> list = new CopyOnWriteArrayList<>();for (int i = 1; i <= 30; i++) {new Thread(() -> {list.add(UUID.randomUUID().toString().toLowerCase().substring(0, 8).replaceAll("-", ""));System.out.println("【当前线程】：" + Thread.currentThread().getName() + "，【当前list】：" + list);}, String.valueOf(i)).start();}}}

二、多线程HashSet集合不安全

2.1、HashSet集合不安全案例代码

/*** @Author : 一叶浮萍归大海* @Date: 2023/11/20 12:38* @Description: 多线层环境下HashSet集合不安全案例代码*/
public class NotSafeHashSetMainApp {public static void main(String[] args) {Set<String> hashSet = new HashSet<>();for (int i = 1; i <= 30; i++) {new Thread(() -> {hashSet.add(UUID.randomUUID().toString().toLowerCase().substring(0, 8).replaceAll("-", ""));System.out.println("【当前线程】：" + Thread.currentThread().getName() + "，【当前hashSet】：" + hashSet);}, String.valueOf(i)).start();}}}

2.2、解决方法

/*** @Author : 一叶浮萍归大海* @Date: 2023/11/20 12:38* @Description: 多线层环境下HashSet集合不安全解决案例代码*/
public class NotSafeHashSetPlusMainApp {public static void main(String[] args) {// Set<String> hashSet = Collections.synchronizedSet(new HashSet<>());Set<String> hashSet = new CopyOnWriteArraySet<>();for (int i = 1; i <= 30; i++) {new Thread(() -> {hashSet.add(UUID.randomUUID().toString().toLowerCase().substring(0, 8).replaceAll("-", ""));System.out.println("【当前线程】：" + Thread.currentThread().getName() + "，【当前hashSet】：" + hashSet);}, String.valueOf(i)).start();}}}

三、多线程HashMap集合不安全

3.1、HashMap集合不安全案例代码

/*** @Author : 一叶浮萍归大海* @Date: 2023/11/20 12:38* @Description: 多线层环境下HashMap集合不安全案例代码*/
public class NotSafeHashMapMainApp {public static void main(String[] args) {HashMap<String,Object> hashMap = new HashMap<>();for (int i = 1; i <= 30; i++) {new Thread(() -> {hashMap.put(UUID.randomUUID().toString().substring(0, 1),UUID.randomUUID().toString().toLowerCase().substring(0, 8).replaceAll("-", ""));System.out.println("【当前线程】：" + Thread.currentThread().getName() + "，【当前hashMap】：" + hashMap);}, String.valueOf(i)).start();}}}

3.2、解决方法

/*** @Author : 一叶浮萍归大海* @Date: 2023/11/20 12:38* @Description: 多线层环境下HashMap集合不安全解决案例代码*/
public class NotSafeHashMapPlusMainApp {public static void main(String[] args) {// Map<String,Object> hashMap = Collections.synchronizedMap(new HashMap<>());Map<String,Object> hashMap = new ConcurrentHashMap<>();for (int i = 1; i <= 30; i++) {new Thread(() -> {hashMap.put(UUID.randomUUID().toString().substring(0, 1),UUID.randomUUID().toString().toLowerCase().substring(0, 8).replaceAll("-", ""));System.out.println("【当前线程】：" + Thread.currentThread().getName() + "，【当前hashMap】：" + hashMap);}, String.valueOf(i)).start();}}}