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:

<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">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.gorkwobble</groupId>
  <artifactId>logmanager</artifactId>
  <name>LogManager</name>
  <version>0.1.0</version>
  <description>Systematically renames specified log files on a scheduled basis. Designed to help manage MUSHClient logging and prevent long, continuous log files.</description>
  <build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-jar-plugin</artifactId>
            <version>2.2</version>
            <!-- nothing here -->
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-assembly-plugin</artifactId>
            <version>2.2-beta-4</version>
            <configuration>
              <descriptorRefs>
                <descriptorRef>jar-with-dependencies</descriptorRef>
              </descriptorRefs>
              <archive>
                <manifest>
                  <mainClass>com.gorkwobble.logmanager.LogManager</mainClass>
                </manifest>
              </archive>
            </configuration>
            <executions>
              <execution>
                <phase>package</phase>
                <goals>
                  <goal>single</goal>
                </goals>
              </execution>
            </executions>
          </plugin>
          <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
              <source>1.6</source>
              <target>1.6</target>
            </configuration>
          </plugin>
    </plugins>
  </build>
  <dependencies>
    <!-- commons-lang -->
    <dependency>
        <groupId>commons-lang</groupId>
        <artifactId>commons-lang</artifactId>
        <version>2.4</version>
    </dependency> 

    <!-- Quartz scheduler -->
    <dependency>
        <groupId>opensymphony</groupId>
        <artifactId>quartz</artifactId>
        <version>1.6.3</version>
    </dependency>
    <!-- Quartz 1.6.0 depends on commons collections -->
    <dependency>
      <groupId>commons-collections</groupId>
      <artifactId>commons-collections</artifactId>
      <version>3.1</version>
    </dependency>
    <!-- Quartz 1.6.0 depends on commons logging -->
    <dependency>
      <groupId>commons-logging</groupId>
      <artifactId>commons-logging</artifactId>
      <version>1.1</version>
    </dependency>
    <!-- Quartz 1.6.0 requires JTA in non J2EE environments -->
    <dependency>
      <groupId>javax.transaction</groupId>
      <artifactId>jta</artifactId>
      <version>1.1</version>
      <scope>runtime</scope>
    </dependency>

    <!-- junitx test assertions -->
    <dependency>
        <groupId>junit-addons</groupId>
        <artifactId>junit-addons</artifactId>
        <version>1.4</version>
        <scope>test</scope>
    </dependency>

    <!-- junit dependency; FIXME: make this a separate POM -->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.1</version>
    </dependency>

  </dependencies>
  <dependencyManagement>
  </dependencyManagement>
</project>

This question is related to java eclipse maven-2 build-process executable-jar

User · Answer

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

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

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