Compiling a Servlet in Ubuntu returns errors

Question

I am attempting to compile source code to be used in a webapp. I know things in Ubuntu are not like things in Windows and that setting classpath permanently is not a good thing to do so I decided to set the flag temporarily. Here is my command in terminal:

littlejavachild@ubuntu:~/LittleJavaChild/ServletProjects/beerV1$ javac -cp "/usr/share/tomcat7/servlet-api.jar" -d classes src/com/example/*.java

What I am trying to achieve is:

compile all the .java files in the package com.example

send the .class files directly to the appropriate directories

copy the classes folder to the WEB-INF folder

Despite setting the classpath I get the errors:

src/com/example/ListenerTester.java:3: error: package javax.servlet does not exist
import javax.servlet.*;
^
src/com/example/ListenerTester.java:4: error: package javax.servlet.http does not exist
import javax.servlet.http.*;
^
src/com/example/ListenerTester.java:7: error: cannot find symbol
public class ListenerTester extends HttpServlet{
                                    ^
  symbol: class HttpServlet
src/com/example/ListenerTester.java:8: error: cannot find symbol
    public void doGet(HttpServletRequest request,
                      ^
  symbol:   class HttpServletRequest
  location: class ListenerTester
src/com/example/ListenerTester.java:9: error: cannot find symbol
                HttpServletResponse response) throws IOException, ServletException {
                ^
  symbol:   class HttpServletResponse
  location: class ListenerTester
src/com/example/ListenerTester.java:9: error: cannot find symbol
                HttpServletResponse response) throws IOException, ServletException {
                                                                  ^
  symbol:   class ServletException
  location: class ListenerTester
src/com/example/MyServletContextListener.java:2: error: package javax.servlet does not exist
import javax.servlet.*;
^
src/com/example/MyServletContextListener.java:4: error: cannot find symbol
public class MyServletContextListener implements ServletContextListener{
                                                 ^
  symbol: class ServletContextListener
src/com/example/MyServletContextListener.java:5: error: cannot find symbol
    public void contextInitialized(ServletContextEvent event){
                                   ^
  symbol:   class ServletContextEvent
  location: class MyServletContextListener
src/com/example/MyServletContextListener.java:12: error: cannot find symbol
    public void contextDestroyed(ServletContextEvent event){
                                 ^
  symbol:   class ServletContextEvent
  location: class MyServletContextListener
src/com/example/ListenerTester.java:14: error: cannot find symbol
        Dog dog = (Dog) getServletContext().getAttribute("dog");
                        ^
  symbol:   method getServletContext()
  location: class ListenerTester
src/com/example/MyServletContextListener.java:6: error: cannot find symbol
        ServletContext sc = event.getServletContext();
        ^
  symbol:   class ServletContext
  location: class MyServletContextListener

I know these errors occur when the classpath is not set properly. Please help me with this. Tell me what is wrong and how do I go about correcting it and how to avoid it in future.

Update with -verbose

[search path for class files: /usr/lib/jvm/java-7-openjdk-i386/jre/lib/resources.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/rt.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/sunrsasign.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/jsse.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/jce.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/charsets.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/netx.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/plugin.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/rhino.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/jfr.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/classes,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/ext/localedata.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/ext/sunjce_provider.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/ext/dnsns.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/ext/java-atk-wrapper.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/ext/pulse-java.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/ext/sunpkcs11.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/ext/zipfs.jar,.,/usr/share/tomcat7/servlet-api.jar]

It is actually usually easier to use an IDE (like eclipse) or a build system like Ant or Maven. I imagine very few java developers actually invoke javac directly. — Tim Bender
@TimBender I was always taught that whenever you learn anything new you should use the text editor and javac. Community member BalusC thinks the same — An SO User
I'd disagree. I think you are running into a peculiarity specific to ubuntu. Also, learning javac will not be the greatest asset to you professionally. You're much better off expending your efforts in learning a build system than you are in struggling with this. — Tim Bender

mtk mtk · Accepted Answer · 2013-02-26T07:05:12

Split the task in bits, and let's just try to compile the java files first. Later check for how to move the class file.

The error indeed says that it didn't find the required class, so the jar isn't added correctly to the classpath. Check this

javac -classpath .:/usr/share/tomcat7/servlet-api.jar src/com/example/*.java

Ensure the jar is present at the given location. Also try running this from the src folder and giving the path as com/example/*.java

Compiling a Servlet in Ubuntu returns errors

Update with -verbose

2 Answers