Mvn install or Mvn package

I am new to Maven, I have a Java based web project with maven configured in my MyEclipse.
Now if I modified any java files then do I need to do Run as -> Mvn install or Mvn package?

from http://maven.apache.org/guides/getting-started/maven-in-five-minutes.html

package: take the compiled code and package it in its distributable format, such as a JAR.

install: install the package into the local repository, for use as a dependency in other projects locally

So the answer to your question is, it depends on whether you want it in installed into your local repo. Install will also run package because it's higher up in the goal phase stack.

mvn install is the option that is most often used.
mvn package is seldom used, only if you're debugging some issue with the maven build process.

See: http://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html

Note that mvn package will only create a jar file.
mvn install will do that and install the jar (and class etc.) files in the proper places if other code depends on those jars.

I usually do a mvn clean install; this deletes the target directory and recreates all jars in that location.
The clean helps with unneeded or removed stuff that can sometimes get in the way.
Rather then debug (some of the time) just start fresh all of the time.

From the Lifecycle reference, install will run the project's integration tests, package won't.

If you really need to not install the generated artifacts, use at least verify.

Also you should note that if your project is consist of several modules which are dependent on each other, you should use "install" instead of "package", otherwise your build will fail, cause when you use install command, module A will be packaged and deployed to local repository and then if module B needs module A as a dependency, it can access it from local repository.

If you're not using a remote repository (like artifactory), use plain old: mvn clean install

Pretty old topic but AFAIK, if you run your own repository (eg: with artifactory) to share jar among your team(s), you might want to use

mvn clean deploy

instead.

This way, your continuous integration server can be sure that all dependencies are correctly pushed into your remote repository. If you missed one, mvn will not be able to find it into your CI local m2 repository.