java - Is static method in JAVA creates a single instance?

Question

I have a doubt.
Suppose in a multithreaded environment 10K users are using a site simultaniously and the site has a static method.
If a static method in JAVA creates a single instance, then the 10k-th user needs to wait for the method until rest of the users complete their usage.
Am I right?
Can anybody please explain?

Answer 1

If a static method in JAVA create a single instance, then 10K th user need to wait for the method untill rest of the usres complete there usage.

Calling a static method doesn't create an instance implicitly. You can do so within the method, of course - but you don't have to.

Nor does creating an instance require a lock - although again, you can add synchronization should you wish to.

So in the case of a simple static method which doesn't need any synchronized access to shared data, there should be no problem with multiple threads calling that method concurrently.

Answer 2

我猜你的意思是像单身人士或工厂，例如

public class X {

    public static X getInstance() {
        return new X();
    }

    private X() {}
}

那么这一切都取决于你在静态方法上做了什么。如果该方法不关心线程（如上面的示例），那么它不应该被同步并且可以并发执行，那么你就错了，因为可以X.getInstance()并发执行并且 10Kth 不必等待之前完成。

如果该方法不能是多线程的，那么它应该是同步的（整个方法或其中的一部分），那么是的，你是对的。

Answer 3

NO..10K th 用户无需等待该方法，直到其余用户完成使用。

因为它不是静态方法不同步......所以多个线程可以访问同一个对象。