when i add apache deryby dependecy it gives error [duplicate]

Solution 1:

mvn clean install -U

-U means force update of snapshot dependencies.

Release dependencies will be updated this way if they have never been previously successfully downloaded. ref: https://stackoverflow.com/a/29020990/32453

Solution 2:

If your local repository is somehow mucked up for release jars as opposed to snapshots (-U and --update-snapshots only update snapshots), you can purge the local repo using the following:

 mvn dependency:purge-local-repository

You probably then want to clean and install again:

 mvn dependency:purge-local-repository clean install

Lots more info available at https://maven.apache.org/plugins/maven-dependency-plugin/examples/purging-local-repository.html

Solution 3:

-U seems to force update of all SNAPSHOT dependencies.

If you want to update a single dependency without clean or -U you could just remove it from your local repo and then build.

The example below if for updating slf4j-api 1.7.1-SNAPSHOT:

rm -rf ~/.m2/repository/org/slf4j/slf4j-api/1.7.1-SNAPSHOT
mvn compile

Solution 4:

All the answers here didn't work for me. I used the hammer method:

find ~/.m2/ -name "*.lastUpdated" | xargs rm

That fixed the problem :-)