Java Static Keyword in Java

Static Keyword

Static is a keyword in java language which is used to allocates the sufficient memory space for the class (variables and methods).In java language these are classified into following types
1.Static Variable
2.Static Method
3.Static Block

Static Variable

class Demo
{
    int x; //  x is a instance variable
    static int y; // y is a class variable
  
    // here x,y are the  Global variables
    
    void show(int z) // z is formal variable
    {
        int p;  // p is a local variable
        if()
        {
            int q; // q is a block variable
        }
    }
}
    

Static Method

If any method preceded by static keyword is known as static method.

static returntype methodname(list of parameters/no parameters)
{
    Statement 1;
    Statement 2;
    ...
    ...
}

  Method:
        1. Static Method
        
        2. Non Static Method
                    a. Concrete Method (Normal Method)
                    b. Abstract Method (Incomplete Method)(Inheritance)
    

class Demo
{
    int x=10;  //non static variable
    static int y=20; // static variable
    
    void show()
    {
        System.out.println(x); // You get output
        System.out.println(y); // You get output
    }
    static void disp()
    {
        //System.out.println(x);  // You get error
        //because static mentods can not accept  non static variables
        System.out.println(y);  // You get output
    }
}

public class Main
{
    public static void main(String args[])
    {
        Demo d=new Demo();
        d.show(); // You get output
        d.disp(); // You get output
        System.out.println(d.x); // You get output
        System.out.println(d.y); // You get output
       
        //Note: By using object we have to call all static and non static variables and methods
        
        //Demo.show(); You Get error
         Demo.disp();  // You get output
         //System.out.println(Demo.x); // You get error
         System.out.println(Demo.y);  // You get output
        
        //Note: By using class we have to call static methods only
    }
}

                                        

Static Block

Static block is used to execute a program without using main method.

static
{
    Statement 1;
    Statement 2;
    ...
    ...
}

class Main
{
    static
    {
        System.out.println("Welcome");
        System.exit(0);
    }
}

It is not available in latest versions(It works only java 6 before versions).