** Difference between NoClassDefFoundError VS ClassNotFoundException in Java **
Both exception due to missing classes in classpath.
First we will see : NoClassDefFoundError
Class Car{
}
Class Demo
{
public static void main(String[] args){
Car car = new Car();
}
}
e:\Binod> javac Demo.java
It will create Demo.class and Car.class
Now you go and delete Car.class
Now
e:\Binod>java Demo
You will get below exception:
Exception in thread "main" java.lang.NoClassDefFoundError: Car
at Demo2.main(Demo.java:9)
Caused by: java.lang.ClassNotFoundException: Car
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
******* Now we will see ClassNotFoundException ********
ClassNotFoundException is a checked Exception derived directly from java.lang.Exception class and you need to provide explicit
handling for it while NoClassDefFoundError is an Error derived from LinkageError.
public class Demo {
public static void main(String[] args) {
try {
Class check = Class.forName("Car");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}
Make sure Car.class should not be there in classpath.
e:\Binod> javac Demo.java
It will create Demo.class only
e:\Binod>java Demo
This time, you will get below exception:
java.lang.ClassNotFoundException: Car
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
NOTE:
ClassNotFoundException comes in java if we try to load a class at run-time using with
Class.forName() or
ClassLoader.loadClass() or
ClassLoader.findSystemClass() method
and requested class is not available in Java.
Both exception due to missing classes in classpath.
First we will see : NoClassDefFoundError
Class Car{
}
Class Demo
{
public static void main(String[] args){
Car car = new Car();
}
}
e:\Binod> javac Demo.java
It will create Demo.class and Car.class
Now you go and delete Car.class
Now
e:\Binod>java Demo
You will get below exception:
Exception in thread "main" java.lang.NoClassDefFoundError: Car
at Demo2.main(Demo.java:9)
Caused by: java.lang.ClassNotFoundException: Car
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
******* Now we will see ClassNotFoundException ********
ClassNotFoundException is a checked Exception derived directly from java.lang.Exception class and you need to provide explicit
handling for it while NoClassDefFoundError is an Error derived from LinkageError.
public class Demo {
public static void main(String[] args) {
try {
Class check = Class.forName("Car");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}
Make sure Car.class should not be there in classpath.
e:\Binod> javac Demo.java
It will create Demo.class only
e:\Binod>java Demo
This time, you will get below exception:
java.lang.ClassNotFoundException: Car
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
NOTE:
ClassNotFoundException comes in java if we try to load a class at run-time using with
Class.forName() or
ClassLoader.loadClass() or
ClassLoader.findSystemClass() method
and requested class is not available in Java.
