[Shell Script]GetJava (get java code from apks instantly) - Galaxy S 4 Developer Discussion [Developers-Only]

I wrote this small shell script that basically extracts classes.dex from an apk/jar, then decompiles the classes.dex to jar classes, extracts the classes and converts them to java code.
Script got posted on the portal (http://www.xda-developers.com/android/getjava-helps-you-convert-apks-into-java-projects/)
Installation: (dont skip this step)
place it in ~/bin, give execute rights and then run
Code:
getjava --getdeps
Usage:
Code:
getjava file.apk [--debug]
--debug param is optional and gives extra output
when entering "getjava apkname.apk" you will get as output a folder called:
apkname.apk_java
which contains the decompiled classes.
obfuscation may scramble the code
Script:
Code:
#!/bin/bash
# getjava v1.0
# to get java code from apks instantly
# by broodplank
#
# Credits:
# Dex2Jar - Google
# JAD - Pavel Kouznetsov
if [[ ( $1 = "--getdeps" ) || ( $2 = "--getdeps" ) ]]; then
echo "Installing required dependencies..."
echo
sudo apt-get install p7zip unzip wget -y
wget -P ~ http://www.broodplank.net/files/getjava_dep.zip
unzip -o ~/getjava_dep.zip -d ~/bin
rm -f ~/getjava_dep.zip
echo "Done, please restart the script"
exit
fi;
if [[ $2 = "--debug" ]]; then
export DEBUGPARAM1="-d -v"
export DEBUGPARAM2="-v"
else
export DEBUGPARAM1=""
export DEBUGPARAM2=""
fi;
if [[ ( $1 = "" ) || ( $1 = "--help" ) || ( $1 = "-help" ) ]]; then
echo "getjava -- get java from apk or jar instantly"
echo "usage: getjava [apk/jar path] [options]"
echo
echo "options:"
echo " --getdeps Installs all required dependencies automatically"
echo " --debug Show additional debugging information"
echo
echo "by broodplank"
exit
else
DIR=${1%/*}
FILE=${1##*/}
EXTENSION=${1##*.}
OUTDIR="${PWD}/${FILE}_out"
fi;
rm -Rf ${OUTDIR}
rm -Rf ${PWD}/${FILE}_java
mkdir -p ${OUTDIR}
7za x -yr -o${OUTDIR} ${1} classes.dex
d2j-dex2jar.sh ${DEBUGPARAM1} -os -ts ${OUTDIR}/classes.dex -o ${OUTDIR}/classes_dex2jar.jar
7za x -yr -o${OUTDIR}/out ${OUTDIR}/classes_dex2jar.jar
find -iname '*.class' -execdir jad ${DEBUGPARAM2} -o -r -s .java -d ${OUTDIR}/java -o {} \;
rm ${OUTDIR}/classes.dex ${OUTDIR}/classes_dex2jar.jar
mv -f ${OUTDIR}/java ${PWD}/${FILE}_java
rm -Rf ${OUTDIR}

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After converted apk to java, the most important question is "did it run on java enabled phone" ?

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z720 said:
After converted apk to java, the most important question is "did it run on java enabled phone" ?
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z720 said:
After converted apk to java, the most important question is "did it run on java enabled phone" ?
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Wat :silly:
So you're actually saying if the java code itself did run on a java enabled phone? which are all android devices. no it does not of course.
or if you mean if you're able to recompile the apk with the decompiled sources? if so, then in some cases you can but mostly on small apps.
the script is made for getting an insight on how the code is built.
defcomg said:
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+1:good:

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broodplank1337 said:
Wat :silly:
So you're actually saying if the java code itself did run on a java enabled phone? which are all android devices. no it does not of course.
or if you mean if you're able to recompile the apk with the decompiled sources? if so, then in some cases you can but mostly on small apps.
the script is made for getting an insight on how the code is built.
+1:good:
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Hey dude,
Congrats! nice work. Have you done a side by side comparison of your script against DED or Android DARE? When I get home tonight I will give it a run and feed you back my results. Have you got a common APK that I could use as a control?
I will send you the resulting decompiled Java classes from DARE for you to look at

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noice great work
any work making a repacker version?

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Jarmezrocks said:
Hey dude,
Congrats! nice work. Have you done a side by side comparison of your script against DED or Android DARE? When I get home tonight I will give it a run and feed you back my results. Have you got a common APK that I could use as a control?
I will send you the resulting decompiled Java classes from DARE for you to look at
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Click to collapse
Thanks! No I haven't done any comparison actually, I just wrote it and shared it on Dev forums, I never expected it to hit the portal so it's still a really simple script, will extend it and make it better. If anyone would like to contribute to the script, take look at github (just made it) https://github.com/broodplank/GetJava
Attached an apk that is not obfuscated and has very decent java output
ayysir said:
noice great work
any work making a repacker version?
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Thanks, well implementing a repacker is not really the idea. it's because almost all apks will not repack successfully. What I can create tho is an option to export it to an eclipse project such as in ApktoJava (my windows version of this tool)

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@broodplank1337
Thx for this great script. This is what I were looking for some years ago. Good work :good:.

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Quick question, how's this different from dex2jar?

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10tacleBoy said:
@broodplank1337
Thx for this great script. This is what I were looking for some years ago. Good work :good:.
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You're welcome it's always handy to have ;p
elesbb said:
Quick question, how's this different from dex2jar?
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Click to collapse
Well if you read the OP you will see that it does more then just convert the dex to a jar file. sine thats the only thing dex2jar can do
I wrote this small shell script that basically extracts classes.dex from an apk/jar, then decompiles the classes.dex to jar classes, extracts the classes and converts them to java code.

---

broodplank1337 said:
Well if you read the OP you will see that it does more then just convert the dex to a jar file. sine thats the only thing dex2jar can do
I wrote this small shell script that basically extracts classes.dex from an apk/jar, then decompiles the classes.dex to jar classes, extracts the classes and converts them to java code.
Click to expand...
Click to collapse
-.- yes i get that. Thats obvious from the thread title.. but you can use JDGui or other tools to get the java source from the jar files.. In terms of conversion, how is this different from dex2jar?

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elesbb said:
-.- yes i get that. Thats obvious from the thread title.. but you can use JDGui or other tools to get the java source from the jar files.. In terms of conversion, how is this different from dex2jar?
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well. JAD and JDgui (which I use in ApktoJava) are class to java decompilers, but dex2jar converts the dalvik byte code (classes.dex) to java classes. so they are very different, also dex2jar always does it's job correctly all the time, while java decompiler tend to fail now and then (to give you a reasonably readable code)

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This will be useful for those beginners for who wants to learn java for android especially like me. Amazing thumps

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broodplank1337 said:
well. JAD and JDgui (which I use in ApktoJava) are class to java decompilers, but dex2jar converts the dalvik byte code (classes.dex) to java classes. so they are very different, also dex2jar always does it's job correctly all the time, while java decompiler tend to fail now and then (to give you a reasonably readable code)
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If i use your script to decompile(dex2jar) systemui.apk.would i able to recompile it
Sent from my GT-S5570 using XDA Premium 4 mobile app

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arpitkh96 said:
If i use your script to decompile(dex2jar) systemui.apk.would i able to recompile it
Sent from my GT-S5570 using XDA Premium 4 mobile app
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I think not, it contains pretty much code and next to that it needs the android environment to be compiled. almost all system apks cannot be recompiled unfortunately

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broodplank1337 said:
I think not, it contains pretty much code and next to that it needs the android environment to be compiled. almost all system apks cannot be recompiled unfortunately
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Ok.(i have android environment)
Sent from my GT-S5570 using XDA Premium 4 mobile app

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One thing that dex2jar has a hard time with is switch/case statements, and big if/then/else ladders. When compiling down to dalvik code, these often get broken out to seemingly random parts of the function with just an if-eqz :labelname and a return statement. This often means that the code for the case statement shows up outside of the switch statement when converted back to .class files.
TLDR: No, most of the time the resulting java code will not recompile without some tweaking.

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Fenny said:
One thing that dex2jar has a hard time with is switch/case statements, and big if/then/else ladders. When compiling down to dalvik code, these often get broken out to seemingly random parts of the function with just an if-eqz :labelname and a return statement. This often means that the code for the case statement shows up outside of the switch statement when converted back to .class files.
TLDR: No, most of the time the resulting java code will not recompile without some tweaking.
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Click to collapse
Its impossible to recompile any java decompiled apk due to resource ids.
Im wondering if this scrip will return the //Internal error// in a lot of apps when decompiling.

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Not the best way to recover your lost work. Tried it on an APK I have written 2 years ago and I can barely recognize my code. Better than nothing I guess, thanks.

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Can someone explain how to exactly use this script and in which bin folder to place it in?