How to make sure that there is just one instance of class in JVM?

Question

I am developing a design pattern, and I want to make sure that here is just one instance of a class in Java Virtual Machine, to funnel all requests for some resource through a s

Answer 1

For that you need to use singleton pattern, I am just posting a demo code for that that may useful for your understanding.

E.g: If I want only one object for this Connect class:

public final class Connect {

    private Connect() {}

    private volatile static Connect connect = null;

    public static Connect getinstance() {
        if(connect == null) {
            synchronized (Connect.class) {
                connect = new Connect();
            }
        }
        return connect;
    }
}

Here the constructor is private, so no one can use new keyword to make a new instance.