oop - Can you tell me which method should be called in inheritance in java? -

   class {     dog()    }    class b extends {     cat()    }    public static void main(string args[]) {     obj1 = new a();     b obj2 = new b();     obj3 = new b();    } 

when class a object created obj1 call dog(),whenclass b's object created obj2 call cat() , dog().but a obj3= new b() created method should called?please answer thanks

to give quick , dirty answer, think mean:

both methods can called. (in example, neither method called because, excluding other errors, aren't calling of methods)

i won't polymorphism try best:

if have:

class {     public void dosomething() {         system.out.println("bark!");     } } 

and

class b extends a{     public void dosomething() {         system.out.println("meow!");     } } 

and

public static void main(string[] args) {         obj1 = new a();         b obj2 = new b();         obj3 = new b();          // , want see happens when do:         obj1.dosomething();         // prints bark!         obj2.dosomething();         // prints meow!         obj3.dosomething();         // prints meow! } 

notice important thing here both classes have exact same name method, though different things!

that (i think) key concept polymorphism trying understand: can redefine method in subclass! however, redefine method, method has have same name! then, compiler pick version of method defined @ lowest level.

in example

class {     public void dog() {         system.out.print("dog!");     } } class b extends {     public void cat() {         system.out.println("cat!");     } }    public static void main(string args[]) {     obj1 = new a();     b obj2 = new b();     obj3 = new b();      obj1.dog()     // method class has, defined. print dog! } 

however, b defines own method, called cat(). can b.cat().

but don't forget: b extends a, has, b has.

so can call b.dog()!

obj3 since linked new b() can call both dog() , cat().

if named same thing, obj3 call version of method defined in class b. however, in case, 2 seperate methods, 1 not overriding other.

to answer question.

if return code, calling a obj3 = new b();

obj3.dosomething(); // prints meow! 

this because defined obj3 new b() takes on method dosomething() in way class b defines it.