static keyword

Anybody would u let me understand the usage of static keyword in java.Most probably what's my exact doubts are why could'nt we override a method that is static and why we could'nt declare a constructor as static.anybody could pls help me

Static for a class field means that there is one and only one instance of the variable. For example:

Now, if I instantiate any number of ExampleClass classes they will all share the same variable. If one class sets "staticVariable" to 10 then all other instances will see it. This has ramifications in multi-threaded programming.

Static can also be used for one-time initialization. A static block will be run only once for any number of the instantiated classes:

The code in the static block will run only once no matter how many instances of ExampleClass are created.

Another usage of static is for methods. Think of a static method as a "global" method on the class. Unlike "normal" methods you can call a static method without creating an instance of the class. So if you had:

Now any other code could just call:

without having to create a new ExampleClass. Static methods only have access to static variables within the class. Normal member variables are not accessible because those are created on a per-instantiation basis. So:

However, in "normal" methods the opposite is not true. You can access a static variable just fine:

But you will need an instantiated version of ExampleClass to call printHello2:

Does this make a bit more sense now?