Is it possible to view bytecode of Class file? [duplicate]

Solution 1:

Yes. You can use the javap command that's included with the JDK to see the byte code of a class. For example:

javap -c com.mypackage.MyClass

There are several libraries and tools that help you to work with Java bytecode, for example ASM and Jasmin.

Solution 2:

The JDK comes with javap which is a tool to disassemble the byte code inside a class file. Editing on byte code level is possible. Have a look at BCEL, a java library designed to read, manipulate and write class files.

A list of tool and libraries to edit byte code can be found on java-net. For example JBE, a Java Byte Code editor that even comes with a GUI.

Solution 3:

To view the bytecodes

Forget javap! The best plugin I have ever used is the "ASM - Bytecode Outline plugin for Eclipse"

http://asm.ow2.org/eclipse/index.html

It is from ASM (a bytecode manipulation framework).

It shows the bytecodes (that you asked for), stack elements (jvm style), and how to generate the same result (to produce the same bytecodes) using the asm framework methods.

Better still is the fact that it does so while you have the source code selected. You don't have to find the .class file in the bin directory to inspect it's bytecode.

To edit them

Using code:

• ASM: Visitors based, very, very fast.
• BCEL: Loads the bytecode as an in memory description of the class file.
• Javassit: the easiest one to use, allows you to do pattern matching and expression replacement.

By hand: JBE