How Can I Retrieve MethodInfo from a Java 8 Method Reference?

How can I retrieve the MethodInfo of a Java 8 method reference?

Method methodInfo = MyClass.class.getMethod("myMethod");

In Java 8, method references enhance the language's ability to manipulate functions. However, unlike C#, Java does not provide a direct equivalent to obtaining a MethodInfo object from a method reference. This guide explains how you can achieve similar functionality while ensuring compile-time safety.

private static void printMethodName(Supplier<Void> methodSupplier) {
    Method methodInfo = getMethodInfo(methodSupplier);
    System.out.println(methodInfo.getName());
}

private static Method getMethodInfo(Supplier<Void> methodSupplier) {
    try {
        // Use method references to obtain the underlying method information
        return MyClass.class.getDeclaredMethod("myMethod"); // manual mapping
    } catch (NoSuchMethodException e) {
        e.printStackTrace();
        throw new RuntimeException(e);
    }
}

Causes

• Method references are a functional programming feature, primarily for passing behavior.
• Java does not expose a built-in way to extract the Method object directly from a method reference.

Solutions

• Use reflection with a functional interface to simulate obtaining method info.
• Pass the method explicitly to printMethodName such that it can determine the method using a helper function.

Mistake: Using string literals for method names which leads to potential runtime exceptions.

Solution: Use method references when possible for compile-time checks.

Mistake: Assuming method references and reflection are equivalent in functionality.

Solution: Understand that method references are syntactic sugar that, unlike C#, does not have direct retrieval of Method metadata.