Static Keyword in Java

Hello friends,
Welcome back 🙂

In this blog, I'm going to cover shortly about static keyword in Java. I'm assuming that you're familiar with the static keyword in java. Because I've written this blog in such a way that here only revision of the use of static keyword and the important points about static keyword which are rarely disclosed. So the first part will just be short description of static keyword, and second part will be the points about which, most of the new-bee or intermediate developers not familiar with. Please comment if anything is missing or not covered in this blog.

1. static member :
    All the non-static variables/member objects of a class are scoped at object level i.e. we can access a class's variable by using instance of that class. But in Java, we can create a class level scoped variable by using static keyword. The static variables can be accessed by using class name i.e. ClassName.staticVar. To declare variable as static, we just need to prepend static keyword before type of that variable.

2. static method :
    Same as static member,  we can declare a method as static which would scoped at class level. The methods declared using static keyword can be accessed by class name i.e. ClassName.staticMethod(). To declare a method as static, we just need to prepend static keyword before return type of that method.

3. static block :
     A static block is the collection of statements which gets executed when class is loaded into the memory by java class loader. This block executes only once when class is loaded. We can have multiple static blocks, there is no any restriction.

4. Inner static class :
     We can use static keyword for the class which is nested into another class. For packaging convenience, we use static class inside a class.

5.  static import :
    We can import static members (all or few) of a class  by using static import to avoid class reference.

6. static method in Interface:
    In Java 8, Java have introduced static methods in interface. Prior to Java 8, we could not write static methods. These static methods are same as static methods in class except:
    A. scope modifiers (private/public/protected) not allowed.
    B. static block still not added in interface.

Notes :
1. Any static member and static block of a class executes in the order they are declared (direction from top to bottom).
2. As the this and super keywords are instance level keywords, these keywords cannot used neither in static block nor in static method.
3. Sometimes you may get asked that can we override static method or not, and answer is no, because static method of base class can be only accessed and used by base class only, and same about derived class. The derived class's static method can only be accessed and used by derived class only. The signature of both base class's method and derived class's method may be same, but there would be no any relation between both that methods.
4. If a class having multiple static blocks, then execution direction will be top to bottom i.e. first static block will execute first, second block will execute after first and so on.

Hoping everything is covered in this article.
Happy learning.
Thanks.
Girish