Is it possible to see JVM opcodes from class file?

Question

This is actually not about decompiling, I don't want to see the source, instead I want to see JVM instructions like invoke some/package/method()V.

Is there a tool for this purpose?

Try [javap](http://docs.oracle.com/javase/8/docs/technotes/tools/) — McDowell, Aug 22 '14 at 08:05

score 5 · Answer 1 · answered Aug 22 '14 at 08:29

5

suppose you have a class file named MyClass.class

you can easily see what JVM instructions constitute your classfile by using a program shipped by jdk itself,in the same bin directory where java and javac exist.

 javap -c MyClass.class

The above command will provide you with what you be be looking for.

answered Aug 22 '14 at 08:29

Abhishek

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THIS is the best answer, as long as using internal JDK things is much more elegant, than anything else, since the question do not specify IDE involved. – user2501323 Jul 05 '21 at 14:36

score 3 · Accepted Answer · answered Aug 22 '14 at 08:14

I am using Eclipse + Bytecode Outline plugin for Eclipse http://andrei.gmxhome.de/bytecode/index.html. THis is how bytecode looks like

  public static main([Ljava/lang/String;)V throws java/io/IOException 
   L0
    LINENUMBER 11 L0
    INVOKESTATIC test/Test.x ()V
   L1
    LINENUMBER 12 L1
    RETURN
...

score 2 · Answer 3 · answered Aug 22 '14 at 08:20

2

Try that: http://set.ee/jbe/

This tool allows you to see opcodes, attributes and edit it. It's really useful, but doesn't work with Java 8 lambdas.

answered Aug 22 '14 at 08:20

Kamil Jarosz

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Is it possible to see JVM opcodes from class file?

3 Answers3