Forgot pattern lock on Samsung Galaxy J3 but want to keep the data
The only way for you to unlock your device would be if you setup a Samsung account while setting up your phone. 


Head into Samsung's Find my Mobile service.
Sign into your Samsung account. If you did not create a Samsung account or do not remember creating one, then try signing in with your Gmail ID and password.
Wait for your device to be located, and then click on More from the right menu.



  


4) Next scroll down and click on Unlock my Device option


  



On the pop-up enter in the password for your Samsung account