Class Loader Subsystem.md

It does dynamic class loading functionality It loads, links. and initializes the class file when it refers to a class for the first time at runtime, not compile time.

Stages

Loading

1. Boot Strap ClassLoader – Responsible for loading classes from the bootstrap classpath, nothing but rt.jar. Highest priority will be given to this loader.
2. Extension ClassLoader – Responsible for loading classes which are inside ext folder (jre\lib).
3. Application ClassLoader –Responsible for loading Application Level Classpath, path mentioned Environment Variable etc.

Linking

1. Verify – Bytecode verifier will verify whether the generated bytecode is proper or not if verification fails we will get the verification error.
2. Prepare – For all static variables memory will be allocated and assigned with default values.
3. Resolve – All symbolic memory references are replaced with the original references from Method Area.

Initialization

All static variables will be assigned with the original values, and the static block will be executed.