Exception in thread "main" java.lang.ClassNotFoundException

ClassNotFoundException

 

The ClassNotFoundException is thrown when an application tries to load in a class through its string name using:

The forName() method in class Class
The findSystemClass() method in class ClassLoader .
The loadClass() method in class ClassLoader.

 

but no definition for the class with the specified name could be found,ie if a class with the given name is not available during loading then this exception would be thrown.

Example:

 

import java.util.*;

import java.io.*;

 import java.lang.reflect.*;

 public class Ex

 {

 public static void main(String args[])

 {

 String name;

 System.out.println("Enter the class to be loaded");

 Scanner in=new Scanner(new InputStreamReader(System.in));

 name=in.next();

try

{

Class cl=Class.forName(name);

System.out.println();

Constructor[] constructors = cl.getDeclaredConstructors();

for (Constructor c : constructors)

System.out.println(c.getName());

Method[] methods = cl.getDeclaredMethods();

for (Method m : methods)

System.out.println( m.getName());

}

catch(ClassNotFoundException e)

{

e.printStackTrace();

}

}

}

The above program will ask the user to enter a class name to display its constructors and methods.If a class with the given name is not available then the ClassNotFoundException will be thrown.