java - 来自 java.util.concurrent 的线程

Question

我有使用线程的代码，但我不使用 java.util.concurrent 中的线程，所以我想更改我的代码，但我有一些问题。

Thread thread = new Thread() {
                    public void run() {
                        doSomething();
                    }
                };

我想使用像这样的线程执行器，那么我该如何做到这一点？在 java.util.concurrent 中是否有类似的方法？我尝试过:

ExecutorService executorService = Executors.newCachedThreadPool();
Runnable runnable = new Runnable() {
                    public void run() {
                        //my code doing something
                    }
                };

我还有:

List<Runnable> threadsList = new ArrayList<Runnable>();

我有方法:

boolean isAllowedCreateNewThread(Runnable taskToRun){
for(int i = 0; i < threadsList.size(); i++){
        Runnable th = threadsList.get(i);
        if(th.isAlive())doSomething(); //isAlive doesn't work since I have runnable instead of Thread
boolean isAllowed = true ;//I have here some bool function but it doesn't matter
    if(isAllowed){
        threadsList.add(taskToRun);
        //service.submit(taskToRun); 
        executorService.execute(taskToRun);
    }
return isAllowed; 
}

如果我有 List<Thread> threadsList = new ArrayList<Thread>();并且不要使用 ExecutorService 并将所有 Runnable 更改为它工作的线程。所以我认为我也必须改变，但如何改变呢？什么是关键字insted Thread？Runnable？或者是其他东西？我还有:

for(int i = 0; i < threadsList.size(); i++){
        Thread th = threadsList.get(i);
        if(th.isAlive())doSomething(); myThreadName.start();

我必须改变isAlive()类似于 java.util.concurrent 中的内容和myThreadName.start();因此，通常我想使用 Thread 类更改此代码，以使用 java.util.concurrent 中的线程进行编码

Answer 1

您可以将您的代码替换为以下代码段。

1. 创建一个 Runnable 类。

   class MyRunable implements Runnable{
       public void run() {
           doSomething();
       }
       private void doSomething() {
           System.out.println("Thread Executing is " + Thread.currentThread().getId());
       }
   }
   

2. 创建具有所需线程数的执行程序服务。这将创建所需数量的线程池。

   int numberOfThreads  = 4;  // number of threads you want to create
   ExecutorService service = Executors.newFixedThreadPool(numberOfThreads);
   

3. 为池中存在的每个线程创建 Runnable 并将其分配给您的执行程序。

   for(int i=0;i<numberOfThreads;i++){
       Runnable myRunable = new MyRunable();
       service.submit(myRunable);
   }
   
   service.shutdown(); // this is a must as not given ,it halts the termination of the program
   

   示例输出

   Thread Executing is 9
   Thread Executing is 10
   Thread Executing is 8
   Thread Executing is 11
   

所以整个代码将如下所示:

class MyRunable implements Runnable {
    public void run() {
        doSomething();
    }

    private void doSomething() {
        System.out.println("Thread Executing is " + Thread.currentThread().getId());
    }

    public static void main(String[] args) {
        int numberOfThreads  = 4;  // number of threads you want to create
        ExecutorService service = Executors.newFixedThreadPool(numberOfThreads);

        for(int i=0;i<numberOfThreads;i++){
            Runnable myRunable = new MyRunable();
            service.submit(myRunable);
        }

        service.shutdown();

    }

}