IntelliJ MySQL

IntelliJ – Connect to MySQL running in Vagrant

The Database feature of IntelliJ/PHPStorm is very powerful compared to the MySQL CLI. It allows your edit your data from the UI easily without writing any MySQL commands.

Here is how you can connect your MySQL server running in a vagrant machine to the IntelliJ’s database feature and improve your productivity during development.

Create a new MySQL Data Source with these basic configuration:

Fill the basic details such as the data source name, host, port, user name, password and the database name.

Make sure you add ?useSSL=false to the JDBC URL after the form is filled. MySQL 5.7+ has SSL enabled by default.

Full JDBC url: jdbc:mysql://localhost:3306/development_database?useSSL=false

Now, with this default configuration, the connection will not work because we need to set the SSH configuration to allow IntelliJ to talk to the MySQL server running within the vagrant VM.

Goto the SSH/SSL tab, select ‘Use SSH tunnel’ and fill-in the details like this:

The value for Private key file should be the one from IdentityFile from your project vagrant directory using this command:

❯ vagrant ssh-config
Host default
  User vagrant
  Port 2222
  UserKnownHostsFile /dev/null
  StrictHostKeyChecking no
  PasswordAuthentication no
  IdentityFile /Users/lrajasekaran/Dropbox/Projects/myproject/.vagrant/machines/default/virtualbox/private_key/private_key
  IdentitiesOnly yes
  LogLevel FATAL

Now click ‘Test Connection’ from this dialog to ensure the SSH connection is working as expected. Once the SSH connection is setup, close this dialog, go to ‘General’ tab and click ‘Test Connection’ to test the actual database connection using the SSH connection made previously. Once this successful, goto ‘Schemas’ tab and select your database name and click ‘Apply’.

Now you can view all your tables from the Database tool window on the right. Right click on any table and click ‘Jump to Editor’ to see the table rows:

Any value can be edited directly from this UI and then saved to the DB by right clicking the row and clicking ‘Submit’


Avoiding Wildcard imports in Java/Kotlin with IntelliJ

What is a wildcard import or a star import?

When you want to import multiple classes from the same package like this:

import com.example.exception.CustomerNotFoundExcetpion
import com.example.exception.ProductNotFoundExcetpion
import com.example.exception.ProductOutOfStockException
import com.example.exception.AdressNotFoundException

Java has an option to combine them into a single line using wildcard imports:

import com.example.exception.*

Is it bad?

Performance-wise, no. Using a wildcard import doesn’t actually import all the classes in the package. When your code is compiled, only the classes used from this package are added to the bytecode. So there is zero performance difference between wildcard import and explicit imports.

Then why should we avoid it?

  • Explicit imports clearly states what external classes the current class is directly using, provided that you don’t leave redundant imports in your code.
  • If there are two classes with the same name from different packages, it can introduce collision when using wildcard imports.
  • When multiple people are working in a project, wildcard imports can create confusion as to which classes are actually imported

Many large Java projects that I have worked with, have a checkstyle rule to disallow wildcard imports for the above reason.

Now that we have understood why explicit imports are better than implicit imports, let’s see how we can make IntelliJ always use explicit imports.

By default, IntelliJ will convert implicit imports into wildcard imports when it sees 5 import statements from the same package.

This setting can however by set to a large value like 99 to prevent the automatic wild card imports.

Goto Preferences -> Editor -> Code Style -> Java (or Kotlin) -> Update the following two values to 99:

  • Class count to use import with ‘*’
  • Names count to use static import

Also remove all the entries from the “Packages to Use Import with ‘*'” table.

Click ‘Apply’ and close the dialog. Now do ‘Optimize Imports’ again to remove the wildcard imports automatically now and in the future.

More ‘Import’ options can be customized with IntelliJ. Follow this link for more customizations:

The default Sun & Google’s Checkstyle rules also recommend avoiding star import by throwing this exception:

(imports) AvoidStarImport: Using the '.*' form of import should be avoided

To add this rule to your checkstyle configuration, add this line:

<module name="AvoidStarImport"/>