how to know if one is extends other's class

[david dabush]

i have two objects and i want to know if one object is extends or implements the other object class or interface.
how do i do it?

[Kemal Sokolovic]

You might want to look at isAssignableFrom method.
Here is an example:

public class ExtendsTest {

    public static void main(String[] args)
    {
        if(Super.class.isAssignableFrom(Sub.class))
        {
            System.out.println("Sub extends Super");
        }
    }

}

class Super { }

class Sub extends Super { }

Edit: Note that you can use the same method to check if a class implements an interface, as noted in the API.

[david dabush]

o.k
thank you its working

[Kemal Sokolovic]

Even for objects of classes that you declare, you can use the same method to check if one extends another, or if one implements interface. Just instead class name use subInstance.getClass(), everything else is the same.
You can also use getSuperclass() method to see if your class or instance of it extends from another class, and getInterfaces() to list all the interfaces your class implements.

Edit: You changed your response in the meantime, so now I see the first answer is suitable for you.

[david dabush]

i have to classes names as strings.
and i want to know if one class extends or implements the othe class;

exapme:
String class1Name, class2Name;

how to know if class class1Name extends or implements class2Name?

[Winston Gutkowski]

david dabush wrote:thank you its working

Maybe it is, but have you asked yourself: Why do I need to know this?

It smacks to me of reflection which, as far as I'm concerned, is either
(a) a last resort
or
(b) suggests bad design

Java is staticallly-typed and reflection is an aberration. Use it at your peril.

You have been warned.

Winston

[Kemal Sokolovic]

david dabush wrote:i have to classes names as strings.
and i want to know if one class extends or implements the othe class;

exapme:
String class1Name, class2Name;

how to know if class class1Name extends or implements class2Name?

In that case check forName method of Class class.

[david dabush]

and how i use reflection so i can turn strings into class?

can you give example?

[Campbell Ritchie]

You don’t need reflection.
And here are two ways of getting a Class object from its name rather than from an instance:-

Class<?> clz = Exception.class;
Class<?> clazz;
try
{
   clazz = Class.forName(
         JOptionPane.showInputDialog(
               null, "Class Name", "Enter the name of a class:- "
         ));
}
catch (ClassNotFoundException cnf)
{
   cnf.printStackTrace();
}
System.out.println(clz);
System.out.println(clazz);

Count the compiler errors before running that code.

[Kemal Sokolovic]

Did you even try to read the API that I pointed you to at the beginning? This is one way to do it:

Class superClass = Class.forName("javax.swing.JComponent");
Class subClass = Class.forName("javax.swing.JButton");