Ubuntu – Download mongodb compass and Install Using the Terminal

You have used both possibilities to install Oracle Java

Delete the folder and start the installation again:

sudo rm -r /usr/lib/jvm/java-8-oracle/jdk1.8.0_66

sudo apt-get install -f
sudo apt-get purge oracle-java8-installer
sudo apt-get install oracle-java8-installer

After that

sudo apt-get install oracle-java8-set-default

Either you use the PPA or the installation with an archive. But not both.

You can recover or set root password without knowing the current one by starting mysql without loading the grant-tables.

Please note the $ in the commands. This is specifying the terminal prompt you see when typing in the command. It's showing it's a line of text, but and actual typed terminal command. The "mysql>" prefix is also a prompt. That is the prompt you get when running mysql interactivately.

This is the cli (command line) to do this:
(Be sure to stop the current server before performing the steps. Only one server can run at a time.)

$ sudo mkdir /var/run/mysqld; sudo chown mysql /var/run/mysqld
$ sudo mysqld_safe --skip-grant-tables&

Now you can log in as root without a password and perform all commands, as in this case, set the root password as root.

$ sudo mysql --user=root mysql

This is the set root password that you will perform inside mysql if you have MySQL 5.6 or below:

mysql> update user set Password=PASSWORD('new-password') where user='root';
flush privileges;

In MySQL 5.7 or above

mysql> update user set authentication_string=PASSWORD('new-password') where user='root';
flush privileges;

From there, quit (kill the running msqld) mysql and start it as normal.

Notes on starting and stopping the mysql service:

Stop mysql:

$ sudo service mysql stop

Start mysql (normal):

$ sudo service mysql start

Kill the temporary mysql safe mode session:

$ sudo mysqladmin shutdown