Question

I am trying to find why the class cant be created as a static? Like:

public static class Qwert {    
    public static void main(String args[]) {
        int x = 12;
        while (x<12) {
            x--;
        }
        System.out.println(" the X value is : "+ x);
    }
}

Answer 1

In Java, the static keyword typically flags a method or field as existing not once per instance of a class, but once ever. A class exists once anyway so in effect, all classes are “static” in this way and all objects are instances of classes.

static does have a meaning for inner classes, which is entirely different: Usually an inner class instance can access the members of an outer class instance that it’s tied to, but if the inner class is static, it does not have such a reference and can be instantiated without an instance of the outer class. Maybe you saw that someplace, then tried to use it on a top-level class, where it isn’t meaningful.

Or maybe you saw it in other languages like C#, whose syntax is an awful lot like Java’s.

(One time I couldn’t figure out why an outer class instance wasn’t being garbage-collected — it was because I was keeping a reference to one of its inner class instances elsewhere, and the inner class was not static and so had a reference to the outer class instance. So by default, I make inner classes static now.)