yuyabuThis is an experiment to try using javap (disassembler) and jad (decompiler) for this Kotlin code.
fun main (args: Array <String>) {
println ("Hello, World!")
}
Code source
https://kotlinlang.org/docs/tutorials/command-line.html
Like other JVM languages, Kotlin is compiled into a class file executable as Java.
We can verify it because javap can display the mnemonic of JVM and decompile as java source code with jad.
Compile this.
kotlinc hello.kt -include-runtime -d hello.jar
Extract jar and use javap, jad for hello.class
jar xf hello.jar
Environment
macOS High Sierra 10
javap (Disassembler)
Preparation
It is unnecessary since it is in the JDK from the beginning
Execution
javap - c HelloKt.class
Result
Compiled from "hello.kt"
public final class HelloKt {
public static final void main (java.lang.String []);
Code:
0: aload_ 0
1: ldc # 9 // String args
3: invokestatic # 15 // Method kotlin / jvm / internal / Intrinsics.checkParameterIsNotNull: (Ljava / lang / Object; Ljava / lang / String;) V
6: ldc # 17 // String Hello, World!
8: astore_1
9: getstatic # 23 // Field java / lang / System.out: Ljava / io / PrintStream;
12: aload_1
13: invokevirtual # 29 // Method java / io / PrintStream.println: (Ljava / lang / Object;) V
16: return
}
jad (decompiler)
Preparation
How to introduce jad
brew tap caskroom / cask
brew install caskroom / cask / jad
Execution
You can display the mnemonic as a comment with the -a option.
Command
$ jad -a HelloKt.class
$ cat HelloKt.jad
import java.io.PrintStream;
import kotlin.jvm.internal.Intrinsics;
public final class HelloKt
{
public static final void main (String args [])
{
Intrinsics.checkParameterIsNotNull (args, "args");
// 0 0: aload_ 0
// 1 1: ldc 1 # 9 <String "args">
// 2 3: invokestatic # 15 <Method void Intrinsics.checkParameterIsNotNull (Object, String)>
String s = "Hello, World!";
// 3 6: ldc 1 # 17 <String "Hello, World!">
// 4 8: astore_ 1
System.out.println (s);
// 5 9: getstatic # 23 <Field PrintStream System.out>
// 6 12: aload - 1
// 7 13: invokevirtual # 29 <Method void PrintStream.println (Object)>
// 8 16: return
}
}
It was easy to introduce and analyze.
I will check how Kotlin specific functions are represented and converted as Java in the future.
