Unable to start laravel development server on linux

I am using laravel 5 for my project and everything has been working fine but recently I am facing this problem which I done understand.

devboy@devboy-hp ~/sonel_ims_project/ims_eneo $ php artisan serve
Laravel development server started on http://localhost:8000/
[Fri Nov 13 12:00:56 2015] Failed to listen on localhost:8000 (reason: Address already in use)

I have tried devboy@devboy-hp ~ $ sudo netstat -plnt and get

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 192.168.122.1:53        0.0.0.0:*               LISTEN      1840/dnsmasq    
tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN      1985/cupsd      
tcp        0      0 127.0.0.1:8888          0.0.0.0:*               LISTEN      7563/php-5.6.3  
tcp        0      0 0.0.0.0:25              0.0.0.0:*               LISTEN      1656/master     
tcp        0      0 0.0.0.0:443             0.0.0.0:*               LISTEN      6966/httpd      
tcp        0      0 0.0.0.0:445             0.0.0.0:*               LISTEN      740/smbd        
tcp        0      0 127.0.0.1:6942          0.0.0.0:*               LISTEN      7442/java       
tcp        0      0 127.0.0.1:8000          0.0.0.0:*               LISTEN      6931/php-5.6.3  
tcp        0      0 0.0.0.0:6667            0.0.0.0:*               LISTEN      1539/ircd       
tcp        0      0 0.0.0.0:139             0.0.0.0:*               LISTEN      740/smbd        
tcp        0      0 127.0.0.1:63342         0.0.0.0:*               LISTEN      7442/java       
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      6966/httpd      
tcp6       0      0 :::21                   :::*                    LISTEN      7337/proftpd: (acce
tcp6       0      0 ::1:631                 :::*                    LISTEN      1985/cupsd      
tcp6       0      0 :::3128                 :::*                    LISTEN      1416/squid3     
tcp6       0      0 :::25                   :::*                    LISTEN      1656/master     
tcp6       0      0 :::445                  :::*                    LISTEN      740/smbd        
tcp6       0      0 :::3306                 :::*                    LISTEN      7343/mysqld     
tcp6       0      0 :::139                  :::*                    LISTEN      740/smbd  

Then I change port like so php artisan serve --port="8888" but get similar error like below after a while:

Laravel development server started on http://localhost:8888/
[Fri Nov 13 12:01:02 2015] Failed to listen on localhost:8888 (reason: Address already in use)

The first time it happened, it was java using port 8000, so I killed the process and started the server and it worked. Upon stopping and restarting, I get the same error. What could be the problem (as I said everything has been working fine except now and I have not done any major update)?

Answer

This is exactly what I did for the problem.

1. I exit PHPStorm
2. sudo netstat -plnt
3. kill 7563 (Process using port 8888)
4. kill 6931 (Process using port 8000)
5. sudo /opt/lampp/lampp restart (Restart my server altogther)
6. php artisan serve
7. Launch PhpStorm

Now everything is working fine. What caused the problem anyway?