Prasad prap

what do you mean by "not working in all scenarios"? Can you clarify a bit?

Hi Everyone,

I have an abstract class for which I want to allow only single level of inheritance.
For e.g:

BaseX.java abstract class BaseX { } SpecialX class SpecialX extends BaseX { }


Here I do not want any other class to extend SpecialX. Can I do anything to BaseX to enforce this single level inheritance? I do not have any control over SpecialX so putting restriction on this wont be a solution.

Thanks

Do have a look at this Stackoverflow

Do check this list over Stackoverflow.com

@Eric

This sample of code still is half complete and says very less as others have stated. Edit your post and paste the entire code. Things will be easier for us rather than we guessing on every thing.

Can you post in sample of your code so that your use case make more sense and clear rather than assumptions?

Please watch the signature correctly.

Its is int compareTo and not String compareTo.

@Daniel never mind. Thats why this is beginner Java. Do not worry. Shoot your efforts.
Whenever you implement an interface you have to write a definition for methods in the interface.

For e.g:
DO NOT COMPILE THIS CODE. Just observe its concept implementation.

public class ClassA implements Comparable { String name; /*other methods*/ // definition for compareTo. As it what it means to compare 2 ClassA objects. @Override public int compareTo(ClassA objA) { return this.name.compareTo(objA.getName); // String class has an in-built method that implements compareTo and hence we can leverage that. } } public static void main(String[] a) { ClassA obj1 = new ClassA("abc"); ClassA obj2 = new ClassA("pqr"); int x = obj1.compareTo(obj1); // return 1, 0, -1 depending on which is greater. Refer [url=http://docs.oracle.com/javase/1.4.2/docs/api/java/lang/Comparable.html]this[/url] for what it means and why do we need to return integer value and not String as you have done. }

So did you get it why this is wrong?

public static Comparator<Camera> ProductNameComparator
= new Comparator<Camera>()
{
public int compare(Camera camera1, Camera camera2)
{
String productName1 = camera1.getProductName(productName);
String productName2 = camera2.getProductName(productName);

return productName1.compareTo(productName2);

}
};

Let me know if you still need elaboration.

Daniel, Can you post just the snippet(No getter/setter) in the code and the exact error at that line. Things will be lot more easier for everyone.

Anyways,

what is this line just above your constructor doing?

Public class camera implements Comparable

1. Public should be "public".
2. Use case not clear.
3. I believe you used the example literally. I can see Fruit references. Check that out.

@Vijay

Check out this link Throwable

Throwable is the parent class for Errors and Exception. So catch block basically catches Throwable class but we usually write catch(Exception e) often because errors are thrown on much serious accounts. Check out this Stackoverflow

Have a close look at this example:
Comparator example


Let me know if you have trouble fitting that in your example.

implement toString method in Tree class such as

@Override public String toString() { String str= ("X="+x); return str; }

Now call

Tree tree = new Tree(20);

System.out.print(tree); // will print X=20

@daniel

Refer this question. StackOverflow- ClassCastException

Remember null pointer exceptions are always due to no object creation.

What I mean to say is that can I get all process and thread information at once?
Like is it possible for me to access any process any thread?