The answer is
I was getting a null pointer exception during project creation related to "Dynamic Web Module".
To get the project to compile (that is, to javax.servlet to import successfully) I had to go to project's Properties, pick Project Facets in the sidebar, tick Dynamic Web Module and click Apply.
Surprisingly, this time "Dynamic Web Module" facet installed correctly, and import started to work.
you can simply copy the servlet-api.jar and copy that jar files into lib folder, which is in WEB-INF.
then just clean and built your project, your errors will be solved.
**OR**
you can directly add jar files to library by using following steps.
- Right click on project.
- Go To Properties.
- Go to Java Build Path.
- Select Add Library option from tabs.
- Add Jar Files
- give path of your
servlet-api.jarfile. - Clean and build your project.
STEP 1
Go to properties of your project ( with Alt+Enter or righ-click )
STEP 2
check on Apache Tomcat v7.0 under Targeted Runtime and it works.
I know this is an old post. However, I observed another instance where in the project already has Tomcat added but we still get this error. Did this to resolve that:
Alt + Enter
Project Facets
On the right, next to details, is another tab "Runtimes".
The installed tomcat server will be listed there. Select it.
Save the configuration and DONE!
Hope this helps someone.
In my case, when I went to the Targetted Runtimes, screen, Tomcat 7 was not listed (disabled) despite being installed.
To fix, I had to go to Preferences->Server->Runtime Environments then uninstall and reinstall Tomcat 7.
For maven projects add following dependancy :
<!-- https://mvnrepository.com/artifact/javax.servlet/servlet-api -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.0.1</version>
<scope>provided</scope>
</dependency>
For gradle projects:
dependencies {
providedCompile group: 'javax.servlet', name: 'javax.servlet-api', version: '3.0.1'
}
or download javax.servlet.jar and add to your project.
From wikipedia.
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HelloWorld extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 " +
"Transitional//EN\">\n" +
"<html>\n" +
"<head><title>Hello WWW</title></head>\n" +
"<body>\n" +
"<h1>Hello WWW</h1>\n" +
"</body></html>");
}
}
This, of course, works only if you have added the servlet-api.jar to Eclipse build path. Typically your application server (e.g Tomcat) will have the right jar file.
Many of us develop in Eclipse via a Maven project. If so,
you can include Tomcat dependencies in Maven via the tomcat-servlet-api and tomcat-jsp-api jars. One exists for each version of Tomcat. Usually adding these with scope provided to your POM is sufficient. This will keep your build more portable.
If you upgrade Tomcat in the future, you simply update the version of these jars as well.
This could be also the reason. i have come up with following pom.xml.
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</exclusion>
</exclusions>
</dependency>
The unresolved issue was due to exclusion of spring-boot-starter-tomcat. Just remove <exclusions>...</exclusions> dependency it will ressolve issue, but make sure doing this will also exclude the embedded tomcat server.
If you need embedded tomcat server too you can add same dependency with compile scope.
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>compile</scope>
</dependency>
Add javax.servlet dependency in pom.xml. Your problem will be resolved.
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.0.1</version>
<scope>provided</scope>
</dependency>
Include servlet-api.jar from your server lib folder.
Do this step
Quick Fix- This worked in Eclipse - Right Click on project -> Properties -> Java Build Path (Tab) -> Add External JARs -> locate the servlet api jar implementation (if Tomcat - its named servlet-api.jar) -> click OK. That's it !!
Little bit difference from Hari:
Right click on project ---> Properties ---> Java Build Path ---> Add Library... ---> Server Runtime ---> Apache Tomcat ----> Finish.
You should above all never manually copy/download/move/include the individual servletcontainer-specific libraries like servlet-api.jar
@BalusC,
I would prefer to use the exact classes that my application is going to use rather than one provided by Eclipse (when I am feeling like a paranoid developer).
Another solution would be to use Eclipse "Configure Build Path" > Libraries > Add External Jars, and add servlet api of whatever Container one chooses to use.
And follow @kaustav datta's solution when using ant to build - have a property like tomcat.home or weblogic.home. However it introduces another constraint that the developer must install Weblogic on his/her local machine if weblogic is being used ! Any other cleaner solution?
Source: Stackoverflow.com