Can you explain what the invoke dynamic command is and in what cases it is used?

invoke dynamic is an instruction in Java bytecode introduced in Java 7 to support dynamic method linking at runtime.

Unlike regular method calls, which are linked at compile-time or class load-time, invoke dynamic allows deferring method resolution until execution, providing greater flexibility.

Main use cases:

• Implementation of dynamic languages on the JVM (e.g., JRuby, Jython).
• Lambda expressions in Java 8 and above (via the invokedynamic mechanism to implement functional interfaces).
• Optimization of calls and performance improvements through caching of dynamically resolved methods.

Example: when compiling a lambda expression, Java creates an invokedynamic call in the bytecode, which at runtime links the lambda expression to a specific method or function.