What is the purpose of ClassLoader?

The ClassLoader in Java is responsible for the dynamic loading of classes into the JVM during program execution. It allows the JVM to find and load class bytecode from various sources (file system, network, JAR archives, etc.).

Main tasks of the ClassLoader:

• Ensure class isolation between different parts of the application or different applications.
• Allow dynamic loading of classes as needed, which is important for plugins, modular systems, and containers.
• Manage the namespace of classes to avoid conflicts.

In the JVM, there is a hierarchy of loaders: Bootstrap ClassLoader (loads core Java classes), Extension ClassLoader, and Application ClassLoader. You can create your own ClassLoader for special tasks, such as loading classes from non-standard sources or implementing hot code replacement.

An example of using a custom ClassLoader could be in a plugin architecture, where plugins are loaded and unloaded dynamically without restarting the application.