Inheritance and static methods

[sovan chatt]

class A
{
static void p(){System.out.println("h1");}
void p1()
{p();p2();}
void p2()
{System.out.println("h2");}
	}
public class Demo extends A
{	static void p()
{System.out.println("h3");}
void p2()
{System.out.println("h4");}
	public static void main(String[] args) {
	new Demo().p1();	
	}
	}

The output of the code is h1 h4;so,the p1 method calls parent class's P() method and child class's P2() method.Which I feel is very confusing.What is the general concept?

[Jeff Verdegan]

The only thing that is runtime polymorphic in Java is a non-private, non-static, non-final method.

In other words, if a method is non-private, non-static, and non-final, then the JVM will decide at runtime which class's implementation of that method to call, based on the runtime class of the object.

For all other methods--all methods that are either private, static, or final (or any combination)--the compiler determines which class's implementation to call, based on the compile-time type of the reference.

public class Parent {
  public static void foo() { System.out.println("Parent foo"); }
  public void bar() { System.out.println("Parent bar"); }
}

public class Child extends Parent {
  public static void foo() { System.out.println("Child foo"); }
  public void bar() { System.out.println("Child bar"); }
}

...

Parent p1 = new Parent();
Parent p2 = new Child();

Child c1 = new Child();

p1.foo(); // "Parent foo" because p1 reference is Parent (compile time)
p1.bar(); // "Parent bar" because p1 points to Parent object (runtime)

p2.foo(); // "Parent foo" because p2 reference is Parent (compile time)
p2.bar(); // "Child bar" because p2 points to Child object (runtime)

c1.foo(); // "Child foo"  because c1 reference is Child (compile time)
c1.bar(); // "Child bar" becuase c1 points to Child object (runtime)