java.net.BindException: Address already in use: JVM_Bind <null>:80

The error:

java.net.BindException: Address already in use: JVM_Bind :80

means that another application is listening on port 80.

You can check which process is using this port by lsof command, e.g. sudo lsof -i:80. Then stop or kill it.

If won't help finding application running on the same port, the common mistake is the Tomcat misconfiguration.

For example by default Tomcat listens on port 8005 for SHUTDOWN command and if you set another Connector to listen on the same port, you'll get port conflict.

So please double check in server.xml whether these ports are different:

<Server port="8005" shutdown="SHUTDOWN">
    <Connector port="8983" protocol="HTTP/1.1"

Setting Tomcat to listen to port 80 is WRONG , for development the 8080 is a good port to use. For production use, just set up an apache that shall forward your requests to your tomcat. Here is a how to.

PID 0 is the System Idle Process, which is surely not listening to port 80. How did you check which process was using the port?

You can use

netstat /nao | findstr "80"

to find the PID and check what process it is.