Xposed Framework

install xposed framework
https://www.apkmirror.com/apk/rovo89/xposed-installer/

then download Wanam Xposed and flash it through twrp
https://androidfilehost.com/?fid=385035244224402234

how to root samsung j3

this works on j320m j320f j320fn j320h

open settings->about device->software info- and tap on build number until you see the message -you are now a developer-

go back to settings->developer options
and enable- OEM unlock- and USB debugging

download odin to a pc
odin3_v3.13.1

download twrp recovery
j320m/f http://www.mediafire.com/file/692de4m23c8dnpl/TWRP_3.0.2-0_SM-J320F.tar.md5/file

j320fn http://www.mediafire.com/file/9vk24882234bk5a/sm-j320fn_twrp_recovery_3.0.2-1.tar/file

j320h https://www.androidfilehost.com/?fid=385035244224387355

download supersu
https://androidfilehost.com/?fid=961840155545568721

install adb driver https://developer.samsung.com/mobile/android-usb-driver.html

start phone in download mode and connect it to the pc (First shut down your device, then power on by simultaneously pressing the power button + home button + volume down key)

run odin and do as in the screenshot

after boot
copy supersu.zip file to your phone and boot into recovery (power off your phone, then hold volume up+power+home button)

tap on install and flash supersu

when you reboot from twrp it asks to install supersu, select (do not install) otherwise you'll get a bootloop

https://forum.xda-developers.com/galaxy-j3-2016/development
http://4pda.ru/forum/index.php?showtopic=734658&st=500#entry49353798

Download Samsung Firmwares

https://updato.com/firmware-archive-select-model

Odin 3.13.1