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To sum up, DJ Java Decompiler can come in handy when you want to disassemble and decompile Java projects, so you need to use the 10 trial uses wisely to be able to evaluate the application and buy a license if you are satisfied with its performance. We at AppsForMyPC have tested and used DJ Java Decompiler and it worked pretty smoothly ? ?.
3) DJ Java Decompiler. This is yet another standalone Windows Application. It is available for Windows XP, Windows 2003, Windows Vista, Windows 7, Windows 8, Windows 8.1 and Windows 10. It can easily decompile complex Java applets and binaries to produce accurate source code. Dj Java Decompiller Full Version For; Dj Java Decompiller.Exe And Eclipse; The most popular versions of this tool that our community members choose are 3.9, 3.1 and 1.8. Most users note that the main disadvantage of this tool is: this tool is not free. Decompile all kinds of code and disassembles VB 56 products. AndroChef Java Decompiler 1.0.0.8 Java Decompiler DJ Java Decompiler 3.12.12 Dj java decompiler AndroChef Java Decompiler 1.0.0.9 Trial DJ Java Decompiler 3.12.12.98 AndroChef Java Decompiler 1.0.0.10.
What is Java Decompiler ?
Java decompiler converts .class file into java source code. In other words, decompiler converts bytecode into readable .java format.You can use java decompiler to look into the code of predefined java classes like HashMap, HashSet , ArrayList etc. You can find out how Sun/Oracle java developers wrote the java classes which are currently used by billion of devices in the world.Java source code from which the .class file has been generated will not exactly match the java source code generated from the java decompiler. But most of the code will be same.
Read Also : Java 8 Features
After installing java, you can find the predefined java classes in the rt.jar inside JRE folder. Unzip rt.jar and all the predefined java classes will be present in the bytecode(.class) format. By using java decompiler, I have written the articles how HashMap works in java, how HashSet works in java. So let's find out best java decompilers which I have used and now I am recommending it to you.
Best Java Decompilers
1. JDProject
JDProject is one of the most frequently used java decompiler offline.It is developed to decompile java 5 or later versions(as of now till java8). It is available for Windows, Mac OS and Linux. It is a best decompiler for eclipse and intellij too as it provides plugin for each platform. JD-Eclipse is a plug-in for the Eclipse platform while JD-Intellij is a plug-in for Intellij IDEA.
You can download JDProject java decompiler from here
2. Procyon
Procyon is a java decompiler developed by Mike Strobel. Procyon decompiler handles java language enhancements from jdk 1.5 and beyond that most other decompilers don't. Procyon does well with enum declarations, annotations and java 8 lambdas and method references. You can find the wiki here comparing Original code, Procyon decompiler code and JD decompiler code. Although wiki above makes Procyon looks good, but I still prefer JDProject over Procyon. Procyon is relatively new and still work in progress.
3. Cavaj Java Decompiler
If you are a Windows user, then Cavaj is a good option as a decompiler. It is simple to use and decompiles nearly any java class file. The main drawback of Cavaj is that it lacks syntax highlighting.
Also, it is not available for Mac or Linux OS. In short, it is a freeware standalone windows application which converts bytecode(.class) files to java source code.
4. DJ Java Decompiler
DJ Java Decompiler is yet another standalone windows application. It is available for Windows XP, Windows 2003, Windows Vista, Windows 7, Windows 8, 8.1 and 10. You don't need to have the JVM (Java Virtual Machine) or any other java JDK installed. The main advantage of DJ Java Decompiler is that you can decompile more than one java class file at one time. DJ Decompiler enables users to users to save, print, edit and compile the generated java code.
5. JBVD
JBVD stands for java bytecode viewer and decompiler. It is based on the javassist open source library. It is only available for Windows OS. JBVD requires java to be installed on your device to work.
6. AndroChef
AndroChef is also a windows based java decompiler application. With AndroChef Java Decompiler you can decompile apk., dex, jar and java class-files. It's simple and easy. AndroidChef supports Windows XP, Windows 2003, Windows Vista, Windows 7, Windows 8, 8.1 and 10. AndroChef successfully decompiles java6, java 7 and java 8 .jar and .class files.
CFR stands for Class File Reader. It is completely written in java 6. It supports latest features of java8 like lambdas while decompiling. You do not need to worry if you are using java 8. The only drawback of this decompiler is that it is not an open source program. Although, it has a command line tool which is ideal in making the decompiling process efficient and faster.
8. Fernflower
Fernflower is an analytical decompiler for java. It is used to decompile class, zip and jar file extensions. It is still under development.
Conclusion
There are many options available for java decompiler. If you have MacOS ,Linux OS or looking for eclipse,intellij plugin then go for JDProject. For Windows OS there are many options available like DJ decompiler, JBVD, AndroChef, Cavaj, JDProject. Please mention in the comments if you come across any java decompiler which is not mention in the above list. Thats all, I have shared the 8 best java decompilers for java developers. (Redirected from Java Decompiler)
A decompiler is a computer program that takes an executable file as input, and attempts to create a high level source file which can be recompiled successfully. It is therefore the opposite of a compiler, which takes a source file and makes an executable. Decompilers are usually unable to perfectly reconstruct the original source code, and as such, will frequently produce obfuscated code. Nonetheless, decompilers remain an important tool in the reverse engineering of computer software.
Introduction[edit]
The term decompiler is most commonly applied to a program which translatesexecutable programs (the output from a compiler) into source code in a (relatively) high level language which, when compiled, will produce an executable whose behavior is the same as the original executable program. By comparison, a disassembler translates an executable program into assembly language (and an assembler could be used to assemble it back into an executable program).
Decompilation is the act of using a decompiler, although the term can also refer to the output of a decompiler. It can be used for the recovery of lost source code, and is also useful in some cases for computer security, interoperability and error correction.[1] The success of decompilation depends on the amount of information present in the code being decompiled and the sophistication of the analysis performed on it. The bytecode formats used by many virtual machines (such as the Java Virtual Machine or the .NET FrameworkCommon Language Runtime) often include extensive metadata and high-level features that make decompilation quite feasible. The presence of debug data can make it possible to reproduce the original variable and structure names and even the line numbers. Machine language without such metadata or debug data is much harder to decompile.[2]
Some compilers and post-compilation tools produce obfuscated code (that is, they attempt to produce output that is very difficult to decompile, or that decompiles to confusing output). This is done to make it more difficult to reverse engineer the executable.
While decompilers are normally used to (re-)create source code from binary executables, there are also decompilers to turn specific binary data files into human-readable and editable sources.[3][4]
Design[edit]
Decompilers can be thought of as composed of a series of phases each of which contributes specific aspects of the overall decompilation process.
Loader[edit]
The first decompilation phase loads and parses the input machine code or intermediate language program's binary file format. It should be able to discover basic facts about the input program, such as the architecture (Pentium, PowerPC, etc.) and the entry point. In many cases, it should be able to find the equivalent of the
main
function of a C program, which is the start of the user written code. This excludes the runtime initialization code, which should not be decompiled if possible. If available the symbol tables and debug data are also loaded. The front end may be able to identify the libraries used even if they are linked with the code, this will provide library interfaces. If it can determine the compiler or compilers used it may provide useful information in identifying code idioms.[5]Disassembly[edit]
The next logical phase is the disassembly of machine code instructions into a machine independent intermediate representation (IR). For example, the Pentium machine instruction
might be translated to the IR
Idioms[edit]
Idiomatic machine code sequences are sequences of code whose combined semantics is not immediately apparent from the instructions' individual semantics. Either as part of the disassembly phase, or as part of later analyses, these idiomatic sequences need to be translated into known equivalent IR. For example, the x86 assembly code:
could be translated to
Some idiomatic sequences are machine independent; some involve only one instruction. For example,
xoreax,eax
clears the eax
register (sets it to zero). This can be implemented with a machine independent simplification rule, such as a = 0
.In general, it is best to delay detection of idiomatic sequences if possible, to later stages that are less affected by instruction ordering. For example, the instruction scheduling phase of a compiler may insert other instructions into an idiomatic sequence, or change the ordering of instructions in the sequence. A pattern matching process in the disassembly phase would probably not recognize the altered pattern. Later phases group instruction expressions into more complex expressions, and modify them into a canonical (standardized) form, making it more likely that even the altered idiom will match a higher level pattern later in the decompilation.
It is particularly important to recognize the compiler idioms for subroutine calls, exception handling, and switch statements. Some languages also have extensive support for strings or long integers.
Program analysis[edit]
Various program analyses can be applied to the IR. In particular, expression propagation combines the semantics of several instructions into more complex expressions. For example,
could result in the following IR after expression propagation:
The resulting expression is more like high level language, and has also eliminated the use of the machine register
eax
. Later analyses may eliminate the ebx
register.Data flow analysis[edit]
The places where register contents are defined and used must be traced using data flow analysis. The same analysis can be applied to locations that are used for temporaries and local data. A different name can then be formed for each such connected set of value definitions and uses. It is possible that the same local variable location was used for more than one variable in different parts of the original program. Even worse it is possible for the data flow analysis to identify a path whereby a value may flow between two such uses even though it would never actually happen or matter in reality. This may in bad cases lead to needing to define a location as a union of types. The decompiler may allow the user to explicitly break such unnatural dependencies which will lead to clearer code. This of course means a variable is potentially used without being initialized and so indicates a problem in the original program.
Type analysis[edit]
A good machine code decompiler will perform type analysis. Here, the way registers or memory locations are used result in constraints on the possible type of the location. For example, an
and
instruction implies that the operand is an integer; programs do not use such an operation on floating point values (except in special library code) or on pointers. An add
instruction results in three constraints, since the operands may be both integer, or one integer and one pointer (with integer and pointer results respectively; the third constraint comes from the ordering of the two operands when the types are different).[6]Various high level expressions can be recognized which trigger recognition of structures or arrays. However, it is difficult to distinguish many of the possibilities, because of the freedom that machine code or even some high level languages such as C allow with casts and pointer arithmetic.
Proshow gold free download. The example from the previous section could result in the following high level code:
Dj Java Decompiler Serial 3.9
Structuring[edit]
The penultimate decompilation phase involves structuring of the IR into higher level constructs such as
while
loops and if/then/else
conditional statements. For example, the machine codecould be translated into:
Unstructured code is more difficult to translate into structured code than already structured code. Solutions include replicating some code, or adding boolean variables.[7]
Code generation[edit]
The final phase is the generation of the high level code in the back end of the decompiler. Just as a compiler may have several back ends for generating machine code for different architectures, a decompiler may have several back ends for generating high level code in different high level languages.
Just before code generation, it may be desirable to allow an interactive editing of the IR, perhaps using some form of graphical user interface. This would allow the user to enter comments, and non-generic variable and function names. However, these are almost as easily entered in a post decompilation edit. The user may want to change structural aspects, such as converting a
while
loop to a for
loop. These are less readily modified with a simple text editor, although source code refactoring tools may assist with this process. The user may need to enter information that failed to be identified during the type analysis phase, e.g. modifying a memory expression to an array or structure expression. Finally, incorrect IR may need to be corrected, or changes made to cause the output code to be more readable.Legality[edit]
The majority of computer programs are covered by copyright laws. Although the precise scope of what is covered by copyright differs from region to region, copyright law generally provides the author (the programmer(s) or employer) with a collection of exclusive rights to the program.[8] These rights include the right to make copies, including copies made into the computer’s RAM (unless creating such a copy is essential for using the program).[9]Since the decompilation process involves making multiple such copies, it is generally prohibited without the authorization of the copyright holder. However, because decompilation is often a necessary step in achieving software interoperability, copyright laws in both the United States and Europe permit decompilation to a limited extent.
In the United States, the copyright fair use defence has been successfully invoked in decompilation cases. For example, in Sega v. Accolade, the court held that Accolade could lawfully engage in decompilation in order to circumvent the software locking mechanism used by Sega's game consoles.[10] Additionally, the Digital Millennium Copyright Act (PUBLIC LAW 105–304[11]) has proper exemptions for both Security Testing and Evaluation in §1205(i), and Reverse Engineering in §1205(f).
In Europe, the 1991 Software Directive explicitly provides for a right to decompile in order to achieve interoperability. The result of a heated debate between, on the one side, software protectionists, and, on the other, academics as well as independent software developers, Article 6 permits decompilation only if a number of conditions are met:
- First, a person or entity must have a licence to use the program to be decompiled.
- Second, decompilation must be necessary to achieve interoperability with the target program or other programs. Interoperability information should therefore not be readily available, such as through manuals or API documentation. This is an important limitation. The necessity must be proven by the decompiler. The purpose of this important limitation is primarily to provide an incentive for developers to document and disclose their products' interoperability information.[12]
- Third, the decompilation process must, if possible, be confined to the parts of the target program relevant to interoperability. Since one of the purposes of decompilation is to gain an understanding of the program structure, this third limitation may be difficult to meet. Again, the burden of proof is on the decompiler.
In addition, Article 6 prescribes that the information obtained through decompilation may not be used for other purposes and that it may not be given to others.
Overall, the decompilation right provided by Article 6 codifies what is claimed to be common practice in the software industry. Few European lawsuits are known to have emerged from the decompilation right. Uttorent com. This could be interpreted as meaning one of three things: 1) the decompilation right is not used frequently and the decompilation right may therefore have been unnecessary, 2) the decompilation right functions well and provides sufficient legal certainty not to give rise to legal disputes or 3) illegal decompilation goes largely undetected. In a recent report regarding implementation of the Software Directive by the European member states, the European Commission seems to support the second interpretation.[13]
Tools[edit]
Decompilers usually target a specific binary format. Some are native instruction sets (eg Intel x86, ARM, MIPS), others are bytecode for virtual machines (Dalvik, Java class files, WebAssembly, Ethereum).
Due to information loss during compilation, decompilation is almost never perfect, and not all decompilers perform equally well for a given binary format. There are studies comparing the performance of different decompilers.[14]
See also[edit]
- JEB Decompiler (Android Dalvik, Intel x86, ARM, MIPS, WebAssembly, Ethereum)
References[edit]
Dj Java Decompiler Download
- ^Van Emmerik, Mike (2005-04-29). 'Why Decompilation'. Program-transformation.org. Retrieved 2010-09-15.
- ^Miecznikowski, Jerome; Hendren, Laurie (2002). 'Decompiling Java Bytecode: Problems, Traps and Pitfalls'. In Horspool, R. Nigel (ed.). Compiler Construction: 11th International Conference, proceedings / CC 2002. Springer-Verlag. pp. 111–127. ISBN3-540-43369-4.
- ^Paul, Matthias R. (2001-06-10) [1995]. 'Format description of DOS, OS/2, and Windows NT .CPI, and Linux .CP files' (CPI.LST file) (1.30 ed.). Archived from the original on 2016-04-20. Retrieved 2016-08-20.
- ^Paul, Matthias R. (2002-05-13). '[fd-dev] mkeyb'. freedos-dev. Archived from the original on 2018-09-10. Retrieved 2018-09-10.
[…] .CPI & .CP codepage file analyzer, validator and decompiler […] Overview on /Style parameters: […] ASM source include files […] Standalone ASM source files […] Modular ASM source files […]
- ^Cifuentes, Cristina; Gough, K. John (July 1995). 'Decompilation of Binary Programs'. Software Practice and Experience. 25 (7): 811–829. CiteSeerX10.1.1.14.8073. doi:10.1002/spe.4380250706.
- ^Mycroft, Alan (1999). 'Type-Based Decompilation'. In Swierstra, S. Doaitse (ed.). Programming languages and systems: 8th European Symposium on Programming Languages and Systems. Springer-Verlag. pp. 208–223. ISBN3-540-65699-5.
- ^Cifuentes, Cristina (1994). 'Chapter 6'. Reverse Compilation Techniques(PDF) (PhD thesis). Queensland University of Technology. Archived(PDF) from the original on 2016-11-22. Retrieved 2019-12-21.)
- ^Rowland, Diane (2005). Information technology law (3 ed.). Cavendish. ISBN1-85941-756-6.
- ^'U.S. Copyright Office - Copyright Law: Chapter 1'.
- ^'The Legality of Decompilation'. Program-transformation.org. 2004-12-03. Retrieved 2010-09-15.
- ^'Digital Millennium Copyright Act'(PDF). US Congress. 1998-10-28. Retrieved 2013-11-15.
- ^Czarnota, Bridget; Hart, Robert J. (1991). Legal protection of computer programs in Europe: a guide to the EC directive. London: Butterworths Tolley. ISBN0-40600542-7.
- ^'EUR-Lex - 52000DC0199 - EN'.
- ^Harrand, Nicolas; Soto-Valero, Cesar; Monperrus, Martin; Baudry, Benoit (2019). 'The Strengths and Behavioral Quirks of Java Bytecode Decompilers'. 19th International Working Conference on Source Code Analysis and Manipulation (SCAM). IEEE: 92–102. arXiv:1908.06895. Bibcode:2019arXiv190806895H. doi:10.1109/SCAM.2019.00019. ISBN978-1-7281-4937-0.
External links[edit]
Look up decompiler in Wiktionary, the free dictionary. |
Wikibooks has a book on the topic of: Reverse Engineering |
Java Decompiler
- Decompilers and Disassemblers at Curlie
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