java - How to run socket server/client from a servlet to give better access on project code and files to Tomcat Server? -

(please read update #3 understand problem now) have written custom sql program gets user commands gui client , sends them server(which contains database) process using sockets.

now i'm trying write web client database using apache tomcat(and jsp).i have put java files socket version src i've learned how use jsp files user can login web page , program check login information pretty way did previous server/client without socket while running tomcat.

at point have made page textarea , submit button run servlet code below upon clicking submit button:

@webservlet("/change") public class sqlcommandsender extends httpservlet {      datastorage ds = new datastorage();     queryparser parser = new queryparser();     query q;     queryresult res;     string textareavalue;      @override     public void dopost(httpservletrequest request, httpservletresponse response) {         try {             textareavalue = request.getparameter("inconsole");             q = parser.parse(textareavalue);             res = ds.execute(q);             system.out.println(res.getmessage());         } catch (exception e) {             e.printstacktrace();         }     } } 

and goes wrong; when submit create table command textarea command processing reaches point new txt file created new table:

  file tablez = new file("/users/sam/documents/intellij projects/login database/c/db/tables/" + table.getname() + ".txt"); 

from found debugging, when run exact same create command server socket code. line runs without problems , table created without error, when run command tomcat; line above throws following exceptions down:

java.io.ioexception: no such file or directory java.io.filenotfoundexception: null/cat1$was.txt (no such file or directory) java.lang.nullpointerexception 

why happen ?

i should emphasis both programs accessing same line of code in same file.and chunk of code receives raw command string , returns log lines in try section of dopost method above.and same lines of code used in socket version execute commands.

update: here's complete stack trace

update2: have found this questions looks somehow problem, still can't understand might others have insight

update 3: latest info have problem stems tomcat server's inability access files way socket server/client can manipulate files. i'm trying run socket server/client previous phase of program servlet .so if can guide me on how run server/client codes in servlet(which done manually before right-click , clicking run button before). edit question match new details after i've solved , seen answers.

p.s. i'm using intellij , tomcat run intellij's plugin in form of java ee web application. have checked , directory correct.as said exact line works previous server/client.

tomcat server threw exception running same line socket server runs correctly because doesn't have same direct access files in src folder socket server/client does.

i solved problem making socket client in servlet , socket server in db , sending command client instead of writing servlet codes ones in question directly made server run database codes without mediator socket server made problems tomcat has restricted access.