In what scenario is a class loader typically used?

A class loader is a crucial component in Java's runtime environment, responsible for dynamically loading classes into the Java Virtual Machine (JVM) during execution. This process allows the JVM to load classes on demand as they are needed, rather than requiring all classes to be loaded upfront.

When a Java application runs, the class loader retrieves the bytecode of a class from either the local file system, a remote source, or a previously loaded class in memory. This dynamic approach allows Java to manage resources more efficiently and enables features such as classpath configurations, which determine where classes are searched for during execution.

This functionality also supports important Java features such as reflection and the use of various Java frameworks that may require loading additional classes at runtime. In contrast, compiling Java code occurs before execution and involves converting Java source files into bytecode, while executing machine code pertains to the step after loading a class, and managing memory allocation relates to resource management handled by the JVM and its garbage collector, not the class loading process itself. Thus, the use of a class loader is distinctly tied to the dynamic loading of classes as needed during an application's execution.