Question

I am trying to use template design pattern so I use abstract class to define my algorithm like this:

abstract class MyTemplate
{
    public void execute()
    {
       //... do something
       doSomething();
    }
    public abstract void doSomethig();
}

In my code I will create an instanceof MyTemplate everytime like this:

MyTemplate cleanUp = new MyTemplate()
{

public void doSomething()
{
// execute cleanup 
}
}
cleanUp.execute();

Is creating a object out of abstract class expensive for JVM?

Thanks,

Sean Nguyen

Answer 1

You’re not really creating an abstract class instance. You’re creating an instance of a concrete class which happens to have no name in your code, created by the Java compiler.

The JVM doesn’t really know or care about that – so it’s only as expensive as creating an instance of any other class which happens to be a subclass of an abstract class. So don’t sweat it 🙂