basic java question...please advice

[Vinod Vijay]

I'm learning Java. I have a parent class with some protected/default methods in it and I have a child class which is extending this Parent class. This child class also have overridden methods from that of its parent class. Both these Parent and Child class are in same package testClasses.
Now I have created another child class which is in different package called testClasses2.
Initial when I tried to create an object of both Parent and Child class located in testClasses package, the complier had shown me error. After that I imported those classes in this new child class as import testClasses.*; which enabled me to create their objects like Child child = new Child(); and Parent parent = new Parent();

My first question is do I need to import always like above in other classes in other packages (java fundamental concept) before I could create new objects, since Parent/Child classes were in same package and also child was extending the parent class is that why I did not get such error message?

Ok I have imported classes into my new child class(in different package) then why I'm not getting the proper string results(defined in methods) like "Vinod Kumar Nair" or "Vinod" by calling like child.getClass().getName() and parent.getClass().getName() ?
See output below

Parent.java:-

/**
 * 
 */
package testClasses;

/**
 * @author vk185
 *
 */
public class Parent {

	/**
	 * @author vk185
	 * @param nam
	 * @return
	 */
	protected String getName(String nam){
		
		String name = nam;
		return name;
	}
	
	
	/**
	 * @author vk185
	 * @return
	 */
	protected String getName(){
	
		String name = "Vinod";
	    return name;
   }
	
	
    String display(){
		String x = "Parent";
	    return x;	
	}
}

Child.java:-

/**
 * 
 */
package testClasses;

/**
 * @author vk185
 *
 */
public class Child extends Parent{

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub

		Child child = new Child();
		String str = child.getName();
		System.out.println("Name "+str);
		
		String str1 = child.getName("Nair");
		System.out.println("My Name is "+str1);
		
		String str2 = child.getName();
		System.out.println("My name is "+str2);
		
		Parent parent = new Parent();
		parent.getName();
		System.out.println(parent.getName());
		
		Parent parent1 = new Child();
		parent1.getName();
		System.out.println(parent1.getName());
		
		
		Child child2 = new Child();
		System.out.println(child2.display());
		
		Parent parent2 = new Parent();
		System.out.println(parent2.display());
		
		Parent parent3 = new Child();
		System.out.println(parent3.display());
		
	
	}

   /**
	* @author vk185
    */
   protected String getName(){
	   
	   String name1 = "Vinod Kumar Nair";
	   return name1;
   }
   
   String display(){
	   String x = "Child";
	   return x;
   }
}

Child2.java :-

 /**
 * 
 */
package testClasses2;
import testClasses.*;

/**
 * @author vk185
 *
 */
public class Child2 {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
    
	Child child = new Child();
	child.getClass().getName();
	System.out.println("@@@ "+child.getClass().getName()+" @@@");
	
	Parent parent = new Parent();
	System.out.println("### "+parent.getClass().getName()+" ###");
	
	Parent parent2 = new Child();
	System.out.println("$$$ "+parent2.getClass().getName()+" $$$");
		
	}

}
  

Why I'm getting the following outputs:-

@@@ testClasses.Child @@@
### testClasses.Parent ###
$$$ testClasses.Child $$$

[Jesper de Jong]

Vinod Vijay wrote:Ok I have imported classes into my new child class(in different package) then why I'm not getting the proper string results(defined in methods) like "Vinod Kumar Nair" or "Vinod" by calling like child.getClass().getName() and parent.getClass().getName() ?

Because for some reason you've put a getClass() call in there, which probably does something completely different than you expect. The getClass() method gets the java.lang.Class object of whatever you're calling it on. The Class object has a getName() method, which returns the name of the class. Note that the getName() method of the Class object does not have anything to do with your own getName() method defined in your classes.

You probably just wanted to call child.getName() and parent.getName(), not child.getClass().getName() and parent.getClass().getName().

Vinod Vijay wrote:Why I'm getting the following outputs:-

@@@ testClasses.Child @@@
### testClasses.Parent ###
$$$ testClasses.Child $$$

Exactly as above; because you're calling the getName() method of the java.lang.Class object, not the getName() method that you defined in your own classes Parent and Child.

[Vinod Vijay]

Jesper de Jong wrote:

Vinod Vijay wrote:Ok I have imported classes into my new child class(in different package) then why I'm not getting the proper string results(defined in methods) like "Vinod Kumar Nair" or "Vinod" by calling like child.getClass().getName() and parent.getClass().getName() ?

Because for some reason you've put a getClass() call in there, which probably does something completely different than you expect. The getClass() method gets the java.lang.Class object of whatever you're calling it on. The Class object has a getName() method, which returns the name of the class. Note that the getName() method of the Class object does not have anything to do with your own getName() method defined in your classes.

You probably just wanted to call child.getName() and parent.getName(), not child.getClass().getName() and parent.getClass().getName().

Vinod Vijay wrote:Why I'm getting the following outputs:-

@@@ testClasses.Child @@@
### testClasses.Parent ###
$$$ testClasses.Child $$$

Exactly as above; because you're calling the getName() method of the java.lang.Class object, not the getName() method that you defined in your own classes Parent and Child.

Thanks...very well explained.....
Yes, it was my silly mistake and I will take care of this in future. I have learnt something from my mistake...