Which exception occurs when a class is not found while dynamically loading a class using the class loaders?

Asked By: Marianna Crespi | Last Updated: 27th June, 2020
Category: technology and computing programming languages
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ClassNotFoundException occurs when class is not found while dynamically loading class - Core Java. Q.

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Similarly one may ask, which exception occurs when a class is not found while dynamically?

As the name suggests, ClassNotFoundException is an exception while NoClassDefFoundError is an error. ClassNotFoundException occurs when classpath is does not get updated with required JAR files while error occurs when required class definition is not present at runtime.

Secondly, how do you handle class not found exception? When you get a ClassNotFoundException, it means the JVM has traversed the entire classpath and not found the class you've attempted to reference. The solution, as so often in the Java world, is to check your classpath. You define a classpath on the command line by saying java -cp and then your classpath.

Likewise, what is a class not found exception?

ClassNotFoundException. ClassNotFoundException is a checked exception which occurs when an application tries to load a class through its fully-qualified name and can not find its definition on the classpath. This occurs mainly when trying to load classes using Class. forName(), ClassLoader.

Which ClassLoader is used to load a class?

Java class loaders are used to load classes at runtime. ClassLoader in Java works on three principle: delegation, visibility and uniqueness. Delegation principle forward request of class loading to parent class loader and only loads the class, if parent is not able to find or load class.

31 Related Question Answers Found

What are the checked exception?

A checked exception is a type of exception that must be either caught or declared in the method in which it is thrown. For example, the java.io.IOException is a checked exception. To understand what a checked exception is, consider the following code: Code section 6.9: Unhandled exception.

What is class not found exception in Java?

The ClassNotFoundException in Java
The ClassNotFoundException is thrown when the Java Virtual Machine (JVM) tries to load a particular class and the specified class cannot be found in the classpath. The ClassNotFoundException is a checked exception and thus, must be declared in a method or constructor's throws clause.

How does compiler identify checked exception?

A compiler for the Java programming language checks, at compile time, that a program contains handlers for checked exceptions, by analyzing which checked exceptions can result from execution of a method or constructor. For each checked exception which is a possible result, the throws clause for the method (§8.4.

How do you create an exception in Java?

You can create your own exceptions in Java.
  1. All exceptions must be a child of Throwable.
  2. If you want to write a checked exception that is automatically enforced by the Handle or Declare Rule, you need to extend the Exception class.
  3. If you want to write a runtime exception, you need to extend the RuntimeException class.

How do I find my Classpath runtime?


Check your runtime classpath by going to Run -> Run Configurations and select your application configuration. Check the classpath setting there. There is another workaround for this also. Eclipse by default will include your output folder (usually named bin) in your classpath.

What is the use of throws keyword in Java?

The Java throws keyword is used to declare an exception. It gives an information to the programmer that there may occur an exception so it is better for the programmer to provide the exception handling code so that normal flow can be maintained. Exception Handling is mainly used to handle the checked exceptions.

What is SQL exception in Java?

An exception that provides information on a database access error or other errors. Each SQLException provides several kinds of information: This is used as the Java Exception message, available via the method getMesage . a "SQLstate" string, which follows either the XOPEN SQLstate conventions or the SQL 99 conventions.

What is the difference between final finally and finalize in Java?

Final class can't be inherited, final method can't be overridden and final variable value can't be changed. Finally is used to place important code, it will be executed whether exception is handled or not. Finalize is used to perform clean up processing just before object is garbage collected. Final is a keyword.

Why do we set classpath in Java?

CLASSPATH: CLASSPATH is an environment variable which is used by Application ClassLoader to locate and load the . class files. The CLASSPATH defines the path, to find third-party and user-defined classes that are not extensions or part of Java platform. Include all the directories which contain .

What is JAR file in Java?


ZIP. A JAR (Java ARchive) is a package file format typically used to aggregate many Java class files and associated metadata and resources (text, images, etc.) into one file for distribution. JAR files are archive files that include a Java-specific manifest file.

How do you make a class immutable in Java?

To create an immutable class in java, you have to do following steps.
  1. Declare the class as final so it can't be extended.
  2. Make all fields private so that direct access is not allowed.
  3. Don't provide setter methods for variables.
  4. Make all mutable fields final so that it's value can be assigned only once.

What is a class in Java?

Classes and Objects in Java. Classes and Objects are basic concepts of Object Oriented Programming which revolve around the real life entities. Class. A class is a user defined blueprint or prototype from which objects are created. It represents the set of properties or methods that are common to all objects of one

What is classpath in eclipse?

Classpath Variables. The build path for a Java project can include source code files, other Java projects, folders containing class files and JAR files. Classpath variables allow you to avoid references to the location of a JAR file or folders on your local file system.

What is the exception hierarchy in Java?

Exception Hierarchy
All exception and errors types are sub classes of class Throwable, which is base class of hierarchy. One branch is headed by Exception. This class is used for exceptional conditions that user programs should catch. NullPointerException is an example of such an exception.

What is ClassLoader in Java with example?


The Java ClassLoader is a part of the Java Runtime Environment that dynamically loads Java classes into the Java Virtual Machine. The Java run time system does not need to know about files and file systems because of classloaders. Java classes aren't loaded into memory all at once, but when required by an application.

How do I use classpath in eclipse?

Setup Class path for the project in Eclipse. Choose "Build Path." Right click on the name of the project that you want to build a classpath for in the Package Explorer bar. Click "Build Path" and then choose "Configure Build Path".