MySQL ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES) (no replies)

I can't make the connection between my java application and Mysql 8.

I didn't change anything in my java program and the connection worked perfectly with Mysql 5 version.

I was using user : "root" and password "root" like always did. The connection between java app and MySQL 8 failed for this user. But was ok between Mysql 5.x and java.

I created another user with another password and the connection between java app and Mysql 8 failed again.

When I enter Mysql via Toad framework using the above two users and passwords, I could make the connection without any problem.

But not with my java application, from where I received the message : "MySQL ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES) "

The same message for the second user I created.

The connector/J was mysql-connector-java-8.0.13.jar

Could anyone tell what has been the problem ?

Thanks