JAVA多线程处理for循环数据

妖狐艹你老母 2024-03-23 13:34 87阅读 0赞

1.  对for循环内数据启用多线程执行，主线程与子线程无先后顺序

public static void main(String[] args) throws InterruptedException {
        
            for (int i = 0; i < 5; i++) {
        
                ThreadUtil.execAsync(() -> {
        
                    try {
        
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
        
                        e.printStackTrace();
                    }
                    System.out.println("线程" + Thread.currentThread().getName() + "执行完");
                });
                System.out.println("第" + i + "个线程");
            }
            System.out.println("完成");
        }

执行结果：  
![在这里插入图片描述][bf1c34f33819454b84224ff1bb4aa910.png]

1.  对for循环内数据启用多线程执行，主线程在所有子线程执行完成之后执行

public static void main(String[] args) throws InterruptedException {
        
            //初始化线程数量
            CountDownLatch countDownLatch = ThreadUtil.newCountDownLatch(5);
            for (int i = 0; i < 5; i++) {
        
                ThreadUtil.execute(() -> {
        
                    try {
        
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
        
                        e.printStackTrace();
                    }
                    System.out.println("线程" + Thread.currentThread().getName() + "执行完");
                    //调用线程计数器-1
                    countDownLatch.countDown();
                });
                System.out.println("第" + i + "个线程");
            }
            //唤醒主线程
            countDownLatch.await();
            System.out.println("完成");
        }

执行结果：  
![在这里插入图片描述][26accee9232147d5ba6a2543f8d662e1.png]

1.  对for循环内数据启用多线程执行，主线程在所有子线程执行完成之后执行

public static void main(String[] args) throws InterruptedException {
        
    
            // 线程个数
            int N = 10;
            // 实例化一个倒计数器，N指定计数个数
            CountDownLatch countDownLatch = new CountDownLatch(N);
            for (int i = 0; i < N; i++) {
        
                new Thread(new Runnable() {
        
                    @Override
                    public void run() {
        
                        try {
        
                            Thread.sleep(5000);
                            System.out.println("子线程" + Thread.currentThread().getName() + "休眠结束");
                        } catch (Exception e) {
        
                            e.printStackTrace();
                        } finally {
        
                        	// 计数减一
                            countDownLatch.countDown(); 
                        }
                    }
                }).start();
            }
            // 阻塞，等待当计数减到0时，执行后面的代码
            countDownLatch.await();
            System.out.println("结束");
        }

执行结果：  
![在这里插入图片描述][3e86343d538145c681bb13ab2f4a2ab0.png]  
4. JAVA多线程10个线程处理1000个数据

public static void main(String[] args) throws Exception {
        
            List<Integer> idList = new ArrayList<>();
            for (int i = 1; i <= 1000; i++) {
        
                idList.add(i);
            }
    
            int threadNum = 10;
            ExecutorService executorService = Executors.newFixedThreadPool(threadNum);
            CountDownLatch countDownLatch = new CountDownLatch(threadNum);
    
            int perSize = idList.size() / threadNum;
            // 定义接受数据集合  多线程情况下，使用线程安全集合
            List<Integer> resultList = Collections.synchronizedList(new ArrayList());
    
            for (int i = 0; i < threadNum; i++) {
        
                MultiThread thread = new MultiThread();
                thread.setIdList(idList.subList(i * perSize, (i + 1) * perSize));
                thread.setCountDownLatch(countDownLatch);
                thread.setResultList(resultList);
                executorService.submit(thread);
            }
            countDownLatch.await();
            executorService.shutdown();
    
            // 查看结果
            System.out.println(resultList.size());
            System.out.println(resultList.stream().sorted().collect(Collectors.toList()));
        }
    }
    
    class MultiThread extends Thread {
        
        private List<Integer> idList;
    
        private CountDownLatch countDownLatch;
    
        private List<Integer> result;
    
        public void setResultList(List<Integer> result) {
        
            this.result = result;
        }
    
        public void setIdList(List<Integer> idList) {
        
            this.idList = idList;
        }
    
        public void setCountDownLatch(CountDownLatch countDownLatch) {
        
            this.countDownLatch = countDownLatch;
        }
    
        @Override
        public void run() {
        
            try {
        
    
                // 数据处理
                for (Integer integer : idList) {
        
                    if (integer % 2 == 0) {
        
                        result.add(integer);
                    }
                }
    
            } catch (Exception e) {
        
                e.printStackTrace();
            } finally {
        
                if (countDownLatch != null) {
        
                    countDownLatch.countDown();
                }
            }
        }

执行结果：  
![在这里插入图片描述][7fc5cd35ba3547f7ad9d026f2d302c21.png]

[bf1c34f33819454b84224ff1bb4aa910.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/23/bbe97c8cc4544a7b90cc1ce161de54e9.png
[26accee9232147d5ba6a2543f8d662e1.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/23/189c1086fbdc45b8bdd409c696ade9dd.png
[3e86343d538145c681bb13ab2f4a2ab0.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/23/b59466d94683442ea5f5f397bdd933ae.png
[7fc5cd35ba3547f7ad9d026f2d302c21.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/23/d8b5bb959a2541b2ba71412f859e9337.png