Complete Guide on What is Static Keyword in Java eBuilderz featured image
Keywords are reserved words in Java that can’t be used as identifiers. In Java, we have 57 keywords in total. Among those keywords is one called Static. In this article, we are going to look at how to apply static in various aspects of programming when using Java.
Here are some of the topics that we are going to cover in this article:
Programmers use static keywords in Java to manage memory. Programmers use it with methods, variables, nested classes, and blocks. With a static keyword, you can share the method of a class or the same variable. You can use it with the same method for every instance of a class or a constant variable. Generally, the main method of a class is labeled static.
You need to precede a static member with the keyword static if you create it. That is the block, variable, method, or nested class. You don’t need any object reference when a member is declared as static since you can access it before creating objects of its class. Being a non-access modifier in Java programming language, this is what you can use the static keyword for:
With an example, we will explain in detail each of these methods to help you understand better.
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Before we show you how to apply static keywords in Java, we will first show you how the Java programming language is enhanced with static blocks.
When you load the class, and you want to do your computation to initialize your static variables, all you need to do is declare a static block to be executed once. The diagram below will help you understand the use of Static Block in a Java program.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | // Java program to demonstrate the use of static blocks import java.util.*; public class BlockExample{ // static variable static int j = 10; static int n; // static block static { System.out.println(“Static block initialized.”); n = j * 8; } public static void main(String[] args) { System.out.println(“Inside main method”); System.out.println(“Value of j : “+j); System.out.println(“Value of n : “+n); } } |
I believe that you have understood what a static block is and how to use it. Next, we will be looking at what static variables are and how they help.
Output:
| 1 2 3 4 | Static block initialized Inside main method Value of j:10 Value of n : 80 |
Declaring a variable as static means that at the class level, a single copy of the variable is created and divided among all objects. In other words, global variables are static variables. The same static valuables are shared with all the instances of the class. You can also create static variables at the class-level only.
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The image below will help us understand what this means:
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 | // Java program demonstrate execution of static blocks and variables import java.util.*; public class VariableExample { // static variable static int j = n(); // static block static { System.out.println(“Inside the static block”); } // static method static int n() { System.out.println(“from n “); return 20; } // static method(main !!) public static void main(String[] args) { System.out.println(“Value of j : “+j); System.out.println(“Inside main method”); } } |
Output:As you can see, by executing the program above, a static block and the variables will be executed in order.
| 1 2 3 4 | from n Inside the static block Value of j: 20 Inside main method |
We trust that we have explained what static variables are clearly. Let’s now explain in detail the meaning of nested classes and Static methods in the Java Static keyword.
A static method refers to a method that is declared with the static keyword. The main ( ) method is a good example of a static method. The following restrictions will be experienced when methods are declared as static:
Here is a diagram that will help you understand what static methods are more clearly:
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 | // java program to demonstrate restriction on static methods public class StaticMethodExample { // static variable static int j = 100; // instance variable int n = 200; // static method static void a() { a = 200; System.out.println(“Print from a”); // Cannot make a static reference to the non-static field b n = 100; // compilation error // Cannot make a static reference to the // non-static method a2() from the type Test a2(); // compilation error // Cannot use super in a static context System.out.println(super.j); // compiler error } // instance method void a2() { System.out.println(“Inside a2”); } public static void main(String[] args) { // main method } } |
Static ClassAs you can see from these examples, restrictions are imposed on static methods. The diagram also shows how you can use the super keyword in the static context. That’s it. We hope that you have understood what Static Methods are. Let us now move to nested classes.
The only time a class static is when it’s a nested class. You don’t need a referral from the Outer class to use a nested static class. This means that non-static members of the Outer class can’t be accessed by a static class.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 | public class NestedExample{ private static String str= “Edureka” //Static class static class MyNestedClass{ //non-static method public void disp(){ System.out.println(str); } } public static void main(String args[]){ NestedExample.MyNestedClass obj = new NestedExample.MyNestedClass(); obj.disp(); } |
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We have shared with you the various applications of the Static Keyword in Java. We believe that you have understood clearly what the Static keyword is and how it is used in Java. We also have other articles about Java on our blog if you need more information.
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