Currently I'm adding external projects to my project in order to use them.
A project member said I should use maven, because you don't want other projects in your project. Maven seems really easy to use, but what happens if the owner decides to remove it?
Does that mean maven can't find the external project and I can't rebuild or clear my project?
what happens if the owner decides to remove it? Does that mean maven can't find the external project and my app won't run anymore?
No. Artifacts on mavenCentral are not allowed to be removed, not even by the owner. So that will not happen.
See Joel Orlina's (Sr. developer at Sonartype) post at https://issues.sonatype.org/browse/OSSRH-13636
Sonatype policy prohibits the removal or other modification of artifacts once they've been published to Central. The reasoning behind this is that if the artifact changes after publication, any builds that already depend on it will break
Central referring to mavenCentral
The reasons he states is very valid and seems to be exactly what made you wonder.
Maven seems really easy to use, but what happens if the owner decides to remove it? Does that mean maven can't find the external project and my app won't run anymore?
To add on, some teams using Maven have their own Artifact Repository server (Artifactory, Sonatype etc) such that dependency resolution does not go through directly to the public repositories. Instead, dependency resolution goes through their Artifact Repository server and a copy of that dependency is cached.
