Static Methods in Java Very useful for Selenium

Java static method

If you apply static keyword with any method, it is known as static method.

• A static method belongs to the class rather than object of a class.
• A static method can be invoked without the need for creating an instance of a class.
• Static method can access static data member and can change the value of it.

Example of static method

1. //Program of changing the common property of all objects(static field).  
2.   
3. class Student9{  
4.      int rollno;  
5.      String name;  
6.      static String college = "ITS";  
7.        
8.      static void change(){  
9.      college = "BBDIT";  
10.      }  
11.   
12.      Student9(int r, String n){  
13.      rollno = r;  
14.      name = n;  
15.      }  
16.   
17.      void display (){System.out.println(rollno+" "+name+" "+college);}  
18.   
19.     public static void main(String args[]){  
20.     Student9.change();  
21.   
22.     Student9 s1 = new Student9 (111,"Karan");  
23.     Student9 s2 = new Student9 (222,"Aryan");  
24.     Student9 s3 = new Student9 (333,"Sonoo");  
25.   
26.     s1.display();  
27.     s2.display();  
28.     s3.display();  
29.     }  
30. }  

Output: 111 Karan BBDIT

           222 Aryan BBDIT

           333 Sonoo BBDIT

Another example of static method that performs normal calculation

1. //Program to get cube of a given number by static method  
2.   
3. class Calculate{  
4.   static int cube(int x){  
5.   return x*x*x;  
6.   }  
7.   
8.   public static void main(String args[]){  
9.   int result=Calculate.cube(5);  
10.   System.out.println(result);  
11.   }  
12. }  

Output:125

Restrictions for static method

There are two main restrictions for the static method. They are:

1. The static method cannot use non static data member or call non-static method directly.
2. this and super cannot be used in static context.
3. class A{  
4.  int a=40;//non static  
5.    
6.  public static void main(String args[]){  
7.   System.out.println(a);  
8.  }  
9. }        

Output:Compile Time Error

Q) why java main method is static?

Ans) because object is not required to call static method if it were non-static method, jvm create object first then call main() method that will lead the problem of extra memory allocation.

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3) Java static block

• Is used to initialize the static data member.
• It is executed before main method at the time of classloading.

Example of static block

1. class A2{  
2.   static{System.out.println("static block is invoked");}  
3.   public static void main(String args[]){  
4.    System.out.println("Hello main");  
5.   }  
6. }  

Output: static block is invoked

       Hello main

Q) Can we execute a program without main() method?

Ans) Yes, one of the way is static block but in previous version of JDK not in JDK 1.7.

1. class A3{  
2.   static{  
3.   System.out.println("static block is invoked");  
4.   System.exit(0);  
5.   }  
6. }  

Output:static block is invoked (if not JDK7)