getParameterTypes

The `getParameterTypes()` method is a Java reflection API function used to retrieve the parameter types of a method, constructor, or method reference. It is part of the `java.lang.reflect.Method`, `java.lang.reflect.Constructor`, and `java.lang.reflect.Executable` interfaces, providing developers with introspection capabilities to analyze method signatures programmatically.

This method returns an array of `Class<?>` objects, each representing the type of a parameter in the order they appear in the method's declaration. For example, if a method is defined as `public void process(String name, int value)`, calling `getParameterTypes()` on its `Method` object would return an array containing `String.class` and `int.class`. The method is particularly useful in frameworks, libraries, and dynamic code generation where runtime analysis of method signatures is required.

The `getParameterTypes()` method is distinct from `getParameterAnnotations()`, which retrieves annotation metadata for each parameter, and `getGenericParameterTypes()`, which provides `Type` objects (including parameterized types and wildcards) for more detailed type information. While `getParameterTypes()` works with raw `Class` objects, it does not account for type erasure in generic contexts, meaning it may not fully reflect generic type information unless combined with `getGenericParameterTypes()`.

This method is commonly used in scenarios such as dependency injection frameworks, where parameter types are needed to resolve dependencies, or in annotation processing tools, where method signatures are analyzed to apply custom logic. It is also useful in debugging and logging tools that require runtime inspection of method calls. The method throws a `SecurityException` if the caller does not have reflection privileges, and a `NullPointerException` if invoked on a null `Method`, `Constructor`, or `Executable` object.