How to get the MethodInfo of a Java method reference?

How to get the MethodInfo of a Java method reference?

In Java, you can use reflection to obtain the MethodInfo of a method reference, although the Java language itself does not provide a direct way to obtain this information. The MethodInfo object would represent information about a method, including its name, return type, parameter types, annotations, etc.

Here's a general outline of how you can obtain the MethodInfo of a method reference using reflection:

  1. Get the Method object representing the method reference.
  2. Extract information about the method using the Method object.

Here's an example of how you might do this:

import java.lang.reflect.Method; import java.util.function.Consumer; public class MethodInfoExample { public static void main(String[] args) throws NoSuchMethodException { // Create a method reference to a method of a functional interface Consumer<String> consumer = System.out::println; // Use reflection to get the MethodInfo Method method = consumer.getClass().getMethod("accept", Object.class); // Extract MethodInfo details String methodName = method.getName(); Class<?> returnType = method.getReturnType(); Class<?>[] parameterTypes = method.getParameterTypes(); // You can extract more information as needed // Print the MethodInfo details System.out.println("Method Name: " + methodName); System.out.println("Return Type: " + returnType.getName()); System.out.println("Parameter Types:"); for (Class<?> paramType : parameterTypes) { System.out.println(" " + paramType.getName()); } } }

In this example:

  • We create a method reference Consumer<String> consumer = System.out::println; that references the println method of the PrintStream class.

  • We use reflection to obtain the Method object representing the accept method of the Consumer functional interface, which corresponds to the method reference.

  • We extract information about the method, such as its name, return type, and parameter types using the Method object.

Please note that this approach works for method references to functional interfaces, where the method reference corresponds to a single method of that interface. For more complex scenarios, where the method reference might refer to multiple methods through inheritance or overloaded methods, obtaining MethodInfo can be more involved and may require additional analysis.

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