static vs non-static Java

Java novices are not much aware of static vs non-static or static to non-static calling. Let us find the rules through a program.

In the following code, show() method is non-static and display() is static. The question is "Can we call a non-static method from static method?". Everyone says simply "no" because it requires an object to call. Anyhow, let us observe the compiler message.

public class Demo
{
  public void show()
  {
    System.out.println("Hello");
  }
  public static void display()
  {
    show( );
  } 
}

Output screen of static vs non-static Java

This is an usual compiler message every Java professional come acrosses.

Now let us see the combinations.

show()	display()	Result
non-static	non-static	works
static	non-static	works
static	static	works
non-static	static	does not work

The above table can easily be remembered. Only one combination does not work – calling non-static member from static member (it requires object).

Anyhow do small programs yourself and check the rules of combinations to have command over coding.

Can a class be static?

No. A class cannot be static. But static classes are possible with inner classes. Read Static Nested Classes.

Pass your comments and suggestions on this tutorial "static vs non-static Java".