Eclipse showing caution sign on the project folder icon whenever I add an external JAR file to the project

Question

I was revisiting how to connect to a database using JDBC in Eclipse .

I created a project ( Dynamic Web Project ) and added the relevant JAR file for database connection in the external JAR files section ( Project Java Build Path --> Libraries --> Add external jars ). But still I was getting the java.lang.ClassNotFoundException .

I went through other posts and found a solution. Someone suggested to copy the JAR file into the WEB-INF/lib folder of the project. I did that and it worked.

Is adding external files like we used to on eclipse still relevant?

Also, I keep getting this caution sign on the projects ( Dynamic Web Projects ) to which I add external JARs.

The same thing is no problem when working on normal java projects.

My eclipse version is Luna, Java version is 8 and Apache version is 7.

Answer 1

What you had done allowed Eclipse to resolve the classes during development but not for deployment.

Since you're building a servlet you have to set up the project in a way that will successfully deploy as a servlet. Moving the jar to WEB-INF/lib works because all the jars in that directory will be on the default classpath for the servlet.