Can you inspect the byte code of a Java 8 lambda at runtime?

Question

If you have an anonymous class like ``` Predicate isEmpty = new Predicate() { public boolean test(String t) { return t.isEmpty(); } }; ``` A library which is passed the reference to `isEmpty` can inspect the byte code to see what it does and possibly manipulate it. Is there a way you can do this for lambdas? ``` Predicate isEmpty = String::isEmpty; ``` e.g Say have this code and byte code ``` public class Main { public static void test(Predicate tester) { System.out.println("tester.getClass()= " + tester.getClass()); System.out.println("tester.getClass().getClassLoader()="+ tester.getClass().getClassLoader()); } public static void main(String... args) { Predicate isEmpty = String::isEmpty; test(isEmpty); } } $ javap -cp . -c -private Main.class Compiled from "Main.java" public class Main { public Main(); Code: 0: aload_0 1: invokespecial #1 // Method java/lang/Object."":()V 4: return public static void test(java.util.function.Predicate

Accepted Answer

If you just want to SEE the bytecode:

```
javap -c -p -v classfile
      ^disassemble
         ^private methods
            ^verbose, including constant pool and bootstrap methods attribute
```

But if you want to try to do this at runtime, you're pretty much out of luck (by design, we don't have anything like Expression Trees), as the other answer suggests.

Can you inspect the byte code of a Java 8 lambda at runtime?

Solution

Problem

Related problems