Comparing two .jar files

Question

How to compare two .jar files? Both of them compiled .class files.

I want a difference in terms of method changes, etc.

Answer 1

• JAPICC using example:

  japi-compliance-checker OLD.jar NEW.jar

  Sample reports for log4j: http://abi-laboratory.pro/java/tracker/timeline/log4j/

  

• PkgDiff , using an example:

  pkgdiff OLD.jar NEW.jar

  See sample report for args4j.

  

• Clirr , using an example:

  java -jar clirr-core-0.6-uber.jar -o OLD.jar -n NEW.jar

Answer 2

• Rename .jar to .zip
• Extract
• Decompile class files with jad
• Recursive diff

Answer 3

If you select two files in IntellijIdea and press Ctrl + D , then it will show you diff. I use Ultimate and don’t know if it will work with Community edition.

Answer 4

I use in ZipDiff lib (there are both Java and ant APIs).

Answer 5

Extract each jar to your directory using the jar command with xvf options. those. jar xvf myjar.jar for each jar.

Then use the UNIX diff to compare the two directories. This will show the differences in the directories. You can use diff -r dir1 dir2 two recursions and show the differences in the text files in each directory (.xml, .properties, etc.).

It will also show if binary class files are different. To really compare class files, you will have to decompile them, as others have noted.

Answer 6

On Linux / CygWin, a handy script I use from time to time:

 #Extract the jar (war or ear) cd dir1 jar xvf jar-file1 for i in `ls *.class` do javap $i > ${i}.txt #list the functions/variables etc done cd dir2 jar xvf jar-file2 for i in `ls *.class` do javap $i > ${i}.txt #list the functions/variables etc done diff -r dir1 dir2 #diff recursively 

Answer 7

Here is my script to execute the process described by sje397:

  #!/bin/sh # Needed if running on Windows FIND="/usr/bin/find" DIFF="diff -r" # Extract the jar (war or ear) JAR_FILE1=$1 JAR_FILE2=$2 JAR_DIR=${PWD} # to assign to a variable TEMP_DIR=$(mktemp -d) echo "Extracting jars in $TEMP_DIR" EXT_DIR1="${TEMP_DIR}/${JAR_FILE1%.*}" EXT_DIR2="${TEMP_DIR}/${JAR_FILE2%.*}" mkdir ${EXT_DIR1} cd ${EXT_DIR1} jar xf ${JAR_DIR}/${JAR_FILE1} jad -d . -o -t2 -safe -space -b -ff -s java -r **/*.class cd .. mkdir ${EXT_DIR2} cd ${EXT_DIR2} jar xf ${JAR_DIR}/${JAR_FILE2} jad -d . -o -t2 -safe -space -b -ff -s java -r **/*.class cd .. # remove class files so the diff is clean ${FIND} ${TEMP_DIR} -name '*.class' | xargs rm # diff recursively 

I can run it on Windows using GIT for Windows. Just open the command prompt. Run bash and then open the script.

Answer 8

Use the Java Decompiler to turn the jar file into a source file, and then use WinMerge for comparison.

You should consult the copyright owner of the source code to make sure this is normal.

Answer 9

Here is a free tool http://www.extradata.com/products/jarc/

Answer 10

Try http://www.osjava.org/jardiff/ - the tool is old and the list of dependencies is large. From the docs, it seems worth a try.

Answer 11

use java decompiler and decompile all .class files and save all files as a project structure.

then use meld diff viewer and compare them as folders.