Static Method in Java

Static user method:

• Every program is a collection of methods.
• Main() method is the starting point of application.
• JVM invokes the main() method automatically.
• We can define user methods depends on application requirement.
• Static methods must be defined with static keyword.

public class Pro
{
     public static void main(String []args)
     {
        System.out.println("main...");
     }
     
     static void test()
     {
         System.out.println("test...");
     }
}

• In the above application, only main() method invokes by default.
• Test() method must be called explicitly by the programmer.
• We access static members(variable, method) using class name.

public class Pro
{
     public static void main(String []args)
     {
        System.out.println("main starts...");
        Pro.test();
        System.out.println("main ends...");
     }
     
     static void test()
     {
         System.out.println("test...");
     }
}

• We can define more than one method in a single class.
• Class members can be defined in any order.
• Methods execute only when we call explicitly.
• Once the method has been defined, we can call as many times depends on requirement.

public class Pro
{
    static void m2()
     {
         System.out.println("In m2");
     }
     
     public static void main(String []args)
     {
        System.out.println("main");
        Pro.m1();
        Pro.m1();
        Pro.m1();
        Pro.m2();
        Pro.m1();
     }
     
     static void m1()
     {
         System.out.println("In m1");
     }
}

• Static block executes before main() method.
• User methods execute only when we invoke

public class Pro
{
    static void fun()
     {
         System.out.println(3);
     }
     
     public static void main(String []args)
     {
        System.out.println(5);
        Pro.fun();
        System.out.println(1);
     }
     
     static
     {
         System.out.println(7);
         Pro.fun();
         System.out.println(4);
     }
}

• Method takes input called arguments.
• Arguments need to place in parenthesis.
• Arguments are working like local variable.
• We access local variables directly.

public class Pro
{
    static int a=10;
    public static void main(String []args)
    {
        Pro.test(20);
        System.out.println(a + Pro.a);
    }
     
    static void test(int a)
    {
        System.out.println(a + Pro.a);
    }
}

public class Pro
{
    static int a;
    static
    {
        Pro.test(10);
    }
    public static void main(String []args)
    {
       System.out.println(Pro.a);
    }
     
    static void test(int a)
    {
       System.out.println(Pro.a);
       Pro.a = a;
    }
}

Analyze the code:

public class Pro
{
    public static void main(String []args)
    {
       Pro.add(10,20);
       Pro.add(34,67);
       Pro.add(-23, 45);
    }
     
    static void add(int a, int b)
    {
       System.out.println("Sum is : " + (a+b));
    }
}