Building executable jar with maven

Question

I am trying to generate an executable jar for a small home project called  logmanager  using maven  just like this   How can I create an executable JAR with dependencies using Maven   I added the snippet shown there to the pom xml  and ran mvn assembly assembly  It generates two jar files in logmanager target  logmanager-0 1 0 jar  and logmanager-0 1 0-jar-with-dependencies jar  I get an error when I double-click on the first jar   Could not find the main class  com gorkwobble logmanager LogManager  Program will exit    A slightly different error when I double-click the jar-with-dependencies jar   Failed to load Main-Class manifest attribute from  C  EclipseProjects logmanager target logmanager-0 1 0-jar-with-dependencies jar   I copied and pasted the path and classname  and checked the spelling in the POM  My main class launches fine from an eclipse launch configuration  Can someone help me figure out why my jar file won t run  Also  why are there two jars to begin with  Let me know if you need more information   Here is the full pom xml  for reference    lt project xmlns  http   maven apache org POM 4 0 0  xmlns xsi  http   www w3 org 2001 XMLSchema-instance  xsi schemaLocation  http   maven apache org POM 4 0 0 http   maven apache org maven-v4 0 0 xsd  gt     lt modelVersion gt 4 0 0 lt  modelVersion gt     lt groupId gt com gorkwobble lt  groupId gt     lt artifactId gt logmanager lt  artifactId gt     lt name gt LogManager lt  name gt     lt version gt 0 1 0 lt  version gt     lt description gt Systematically renames specified log files on a scheduled basis  Designed to help manage MUSHClient logging and prevent long  continuous log files  lt  description gt     lt build gt       lt plugins gt           lt plugin gt               lt groupId gt org apache maven plugins lt  groupId gt               lt artifactId gt maven-jar-plugin lt  artifactId gt               lt version gt 2 2 lt  version gt               lt  -- nothing here -- gt           lt  plugin gt           lt plugin gt               lt groupId gt org apache maven plugins lt  groupId gt               lt artifactId gt maven-assembly-plugin lt  artifactId gt               lt version gt 2 2-beta-4 lt  version gt               lt configuration gt                 lt descriptorRefs gt                   lt descriptorRef gt jar-with-dependencies lt  descriptorRef gt                 lt  descriptorRefs gt                 lt archive gt                   lt manifest gt                     lt mainClass gt com gorkwobble logmanager LogManager lt  mainClass gt                   lt  manifest gt                 lt  archive gt               lt  configuration gt               lt executions gt                 lt execution gt                   lt phase gt package lt  phase gt                   lt goals gt                     lt goal gt single lt  goal gt                   lt  goals gt                 lt  execution gt               lt  executions gt             lt  plugin gt             lt plugin gt               lt groupId gt org apache maven plugins lt  groupId gt               lt artifactId gt maven-compiler-plugin lt  artifactId gt               lt configuration gt                 lt source gt 1 6 lt  source gt                 lt target gt 1 6 lt  target gt               lt  configuration gt             lt  plugin gt       lt  plugins gt     lt  build gt     lt dependencies gt       lt  -- commons-lang -- gt       lt dependency gt           lt groupId gt commons-lang lt  groupId gt           lt artifactId gt commons-lang lt  artifactId gt           lt version gt 2 4 lt  version gt       lt  dependency gt         lt  -- Quartz scheduler -- gt       lt dependency gt           lt groupId gt opensymphony lt  groupId gt           lt artifactId gt quartz lt  artifactId gt           lt version gt 1 6 3 lt  version gt       lt  dependency gt       lt  -- Quartz 1 6 0 depends on commons collections -- gt       lt dependency gt         lt groupId gt commons-collections lt  groupId gt         lt artifactId gt commons-collections lt  artifactId gt         lt version gt 3 1 lt  version gt       lt  dependency gt       lt  -- Quartz 1 6 0 depends on commons logging -- gt       lt dependency gt         lt groupId gt commons-logging lt  groupId gt         lt artifactId gt commons-logging lt  artifactId gt         lt version gt 1 1 lt  version gt       lt  dependency gt       lt  -- Quartz 1 6 0 requires JTA in non J2EE environments -- gt       lt dependency gt         lt groupId gt javax transaction lt  groupId gt         lt artifactId gt jta lt  artifactId gt         lt version gt 1 1 lt  version gt         lt scope gt runtime lt  scope gt       lt  dependency gt        lt  -- junitx test assertions -- gt       lt dependency gt           lt groupId gt junit-addons lt  groupId gt           lt artifactId gt junit-addons lt  artifactId gt           lt version gt 1 4 lt  version gt           lt scope gt test lt  scope gt       lt  dependency gt        lt  -- junit dependency  FIXME  make this a separate POM -- gt       lt dependency gt         lt groupId gt junit lt  groupId gt         lt artifactId gt junit lt  artifactId gt         lt version gt 4 1 lt  version gt       lt  dependency gt      lt  dependencies gt     lt dependencyManagement gt     lt  dependencyManagement gt   lt  project gt

User · Answer

If you don t want execute assembly goal on package  you can use next command   mvn package assembly single   Here package is keyword

User · Answer

The answer of Pascal Thivent helped me out  too   But if you manage your plugins within the  lt pluginManagement gt element  you have to define the assembly again outside of the plugin management  or else the dependencies are not packed in the jar if you run mvn install    lt project xmlns  http   maven apache org POM 4 0 0  xmlns xsi  http   www w3 org 2001 XMLSchema-instance      xsi schemaLocation  http   maven apache org POM 4 0 0 http   maven apache org xsd maven-4 0 0 xsd  gt       lt modelVersion gt 4 0 0 lt  modelVersion gt       lt version gt 1 0 0-SNAPSHOT lt  version gt       lt packaging gt jar lt  packaging gt         lt build gt           lt pluginManagement gt               lt plugins gt                    lt plugin gt                       lt groupId gt org apache maven plugins lt  groupId gt                       lt artifactId gt maven-compiler-plugin lt  artifactId gt                       lt version gt 3 1 lt  version gt                       lt configuration gt                           lt source gt 1 6 lt  source gt                           lt target gt 1 6 lt  target gt                       lt  configuration gt                   lt  plugin gt                    lt plugin gt                       lt groupId gt org apache maven plugins lt  groupId gt                       lt artifactId gt maven-assembly-plugin lt  artifactId gt                       lt version gt 2 4 lt  version gt                       lt configuration gt                           lt archive gt                               lt manifest gt                                   lt mainClass gt main App lt  mainClass gt                               lt  manifest gt                           lt  archive gt                           lt descriptorRefs gt                               lt descriptorRef gt jar-with-dependencies lt  descriptorRef gt                           lt  descriptorRefs gt                       lt  configuration gt                       lt executions gt                           lt execution gt                               lt id gt make-assembly lt  id gt                               lt phase gt package lt  phase gt                               lt goals gt                                   lt goal gt single lt  goal gt                               lt  goals gt                           lt  execution gt                       lt  executions gt                   lt  plugin gt                lt  plugins gt            lt  pluginManagement gt            lt plugins gt   lt  -- did NOT work without this  -- gt               lt plugin gt                   lt groupId gt org apache maven plugins lt  groupId gt                   lt artifactId gt maven-assembly-plugin lt  artifactId gt               lt  plugin gt           lt  plugins gt        lt  build gt         lt dependencies gt          lt  --  dependencies commented out to shorten example -- gt       lt  dependencies gt    lt  project gt

User · Answer

Actually  I think that the answer given in the question you mentioned is just wrong  UPDATE - 20101106  someone fixed it  this answer refers to the version preceding the edit  and this explains  at least partially  why you run into troubles    It generates two jar files in logmanager target  logmanager-0 1 0 jar  and logmanager-0 1 0-jar-with-dependencies jar   The first one is the JAR of the logmanager module generated during the package phase by jar jar  because the module has a packaging of type jar   The second one is the assembly generated by assembly assembly and should contain the classes from the current module and its dependencies  if you used the descriptor jar-with-dependencies    I get an error when I double-click on the first jar  Could not find the main class  com gorkwobble logmanager LogManager  Program will exit    If you applied the suggested configuration of the link posted as reference  you configured the jar plugin to produce an executable artifact  something like this     lt plugin gt       lt groupId gt org apache maven plugins lt  groupId gt       lt artifactId gt maven-jar-plugin lt  artifactId gt       lt configuration gt         lt archive gt           lt manifest gt             lt addClasspath gt true lt  addClasspath gt             lt mainClass gt com gorkwobble logmanager LogManager lt  mainClass gt           lt  manifest gt         lt  archive gt       lt  configuration gt     lt  plugin gt   So logmanager-0 1 0 jar is indeed executable but 1  this is not what you want  because it doesn t have all dependencies  and 2  it doesn t contain com gorkwobble logmanager LogManager  this is what the error is saying  check the content of the jar    A slightly different error when I double-click the jar-with-dependencies jar  Failed to load Main-Class manifest attribute from  C  EclipseProjects logmanager target logmanager-0 1 0-jar-with-dependencies jar   Again  if you configured the assembly plugin as suggested  you have something like this     lt plugin gt       lt groupId gt org apache maven plugins lt  groupId gt       lt artifactId gt maven-assembly-plugin lt  artifactId gt       lt configuration gt         lt descriptorRefs gt           lt descriptorRef gt jar-with-dependencies lt  descriptorRef gt         lt  descriptorRefs gt       lt  configuration gt     lt  plugin gt   With this setup  logmanager-0 1 0-jar-with-dependencies jar contains the classes from the current module and its dependencies but  according to the error  its META-INF MANIFEST MF doesn t contain a Main-Class entry  its likely not the same MANIFEST MF as in logmanager-0 1 0 jar   The jar is actually not executable  which again is not what you want   So  my suggestion would be to remove the configuration element from the maven-jar-plugin and to configure the maven-assembly-plugin like this     lt plugin gt       lt groupId gt org apache maven plugins lt  groupId gt       lt artifactId gt maven-jar-plugin lt  artifactId gt       lt version gt 2 2 lt  version gt       lt  -- nothing here -- gt     lt  plugin gt     lt plugin gt       lt groupId gt org apache maven plugins lt  groupId gt       lt artifactId gt maven-assembly-plugin lt  artifactId gt       lt version gt 2 2-beta-4 lt  version gt       lt configuration gt         lt descriptorRefs gt           lt descriptorRef gt jar-with-dependencies lt  descriptorRef gt         lt  descriptorRefs gt         lt archive gt           lt manifest gt             lt mainClass gt org sample App lt  mainClass gt           lt  manifest gt         lt  archive gt       lt  configuration gt       lt executions gt         lt execution gt           lt phase gt package lt  phase gt           lt goals gt             lt goal gt single lt  goal gt           lt  goals gt         lt  execution gt       lt  executions gt     lt  plugin gt   Of course  replace org sample App with the class you want to have executed  Little bonus  I ve bound assembly single to the package phase so you don t have to run assembly assembly anymore  Just run mvn install and the assembly will be produced during the standard build  So  please update your pom xml with the configuration given above and run mvn clean install  Then  cd into the target directory and try again  java -jar logmanager-0 1 0-jar-with-dependencies jar  If you get an error  please update your question with it and post the content of the META-INF MANIFEST MF file and the relevant part of your pom xml  the plugins configuration parts   Also please post the result of  java -cp logmanager-0 1 0-jar-with-dependencies jar com gorkwobble logmanager LogManager  to demonstrate it s working fine on the command line  regardless of what eclipse is saying   EDIT  For Java 6  you need to configure the maven-compiler-plugin  Add this to your pom xml     lt plugin gt       lt groupId gt org apache maven plugins lt  groupId gt       lt artifactId gt maven-compiler-plugin lt  artifactId gt       lt configuration gt         lt source gt 1 6 lt  source gt         lt target gt 1 6 lt  target gt       lt  configuration gt     lt  plugin gt

User · Answer

Right click the project and give maven build maven clean maven generate resource and maven install The jar file will automatically generate

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