Unable to execute jar- file no main manifest attribute

Question

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I have installed an application, when I try to run it (it's an executable jar) nothing happens. When I run it from the commandline with:

java -jar "app.jar"

I get the following message:

no main manifest attribute, in "app.jar"

Normally, if I had created the program myself, I would have added a main class attribute to the manifest file. But in this case, since the file is from an application, i cannot do that. I also tried extracting the jar to see if I could find the main class, but there are to many classes and none of them has the word "main" in it's name. There must be a way to fix this because the program runs fine on other systems.

Answer 1

That should have been java -jar app.jar instead of java -jar "app".

The -jar option only works if the JAR file is an executable JAR file, which means it must have a manifest file with a Main-Class attribute in it. See Packaging Programs in JAR Files to learn how to create an executable JAR.

If it's not an executable JAR, then you'll need to run the program with something like:

java -cp app.jar com.somepackage.SomeClass

where com.somepackage.SomeClass is the class that contains the main method to run the program. (What that class is depends on the program, it's impossible to tell from the information you've supplied).

Answer 2

add a jar/manifest/attributes setting like this:

apply plugin: 'java'
jar {
    manifest {
        attributes 'Main-Class': 'com.package.app.Class'
    }
}

Comments

I got error like this.c an you please tell me the solution for this error?

"C:\Program Files\Android\Android Studio\jre\bin\java.exe" -Dfile.encoding=windows-1252 -jar C:\Users\lb53616\Documents\cyient\watermarkImagesWorkspace\gradle\wrapper\gradle-wrapper.jar
no main manifest attribute, in C:\Users\lb53616\Documents\cyient\watermarkImagesWorkspace\gradle\wrapper\gradle-wrapper.jar

Process finished with exit code 1

---

You might get this error when the Main-Class entry is missing in MANIFEST. MF file. You can put the maven-jar-plugin plugin in pom. xml to fix it.

Answer 3

Main-class property is missing on your jars META-INF/MANIFEST.MF. Correct it by adding the following lines to your pom.xml

build>
<plugins>
<plugin>
<!-- Build an executable JAR -->
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.4</version>
<configuration>
<archive>
<manifest>
<mainClass>com.roufid.tutorials.AppTest</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
</plugins>

Answer 4

Try adding this to your jar file:

java -cp yourJarName.jar your.package..your.MainClass

Answer 5

Try this command to include the jar:

java -cp yourJarName.jar your.package..your.MainClass

Answer 6

When I got the problem I re-created the jar artifact, choosing JAR > From modules with dependencies, but not accepting the default Directory for META-INF/MANIFEST.MF.
Change it from -/src/main/java to -/src/main/resources.

Answer 7

I had the manifest file in correct place, containing the Main-Class and everything. What tripped me over was this:

Warning: The text file from which you are creating the manifest must end with a new line or carriage return. The last line will not be parsed properly if it does not end with a new line or carriage return.

Adding a newline at the end of the manifest fixed it.

Answer 8

I had the same issue. by adding following lines to pom file made it work.
The plugin will make sure the build process of your application with all necessary steps.

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

Answer 9

If u're using gradle, just add next one in ur gradle.build:

apply plugin: 'java'

jar {
    manifest {
        attributes 'Main-Class': 'com.company.project.MainClass'
    }
}

Answer 10

You Can Simply follow this step Create a jar file using

 jar -cfm jarfile-name manifest-filename Class-file name

While running the jar file simple run like this

 java -cp jarfile-name main-classname

Answer 11

I made a calculator using Java AWT completely by hand, no IDE, just notepad++, and compiled the program. This made two class files, one is basically the calculator graphics class and the other is the main class, with the main method which creates the calculator (i.e. I didn't include the main method inside the calculator class, I instead included it in a separate class).

Answer 12

First, it's kind of weird, to see you run java -jar "app" and not java -jar app.jar

Second, to make a jar executable... you need to jar a file called META-INF/MANIFEST.MF

the file itself should have (at least) this one-liner:

Main-Class: com.mypackage.MyClass

Where com.mypackage.MyClass is the class holding the public static void main(String[] args) entry point.

Note that there are several ways to get this done either with the CLI, Maven, Ant or Gradle:

For CLI, the following command will do:

jar cmvf META-INF/MANIFEST.MF <new-jar-filename>.jar  <files to include>

For Maven, something like the following snippet should do the trick. Note that this is only the plugin definition, not the full pom.xml:

<build>
  <plugins>
    <plugin>
      <!-- Build an executable JAR -->
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-jar-plugin</artifactId>
      <version>3.1.0</version>
      <configuration>
        <archive>
          <manifest>
            <addClasspath>true</addClasspath>
            <classpathPrefix>lib/</classpathPrefix>
            <mainClass>com.mypackage.MyClass</mainClass>
          </manifest>
        </archive>
      </configuration>
    </plugin>
  </plugins>
</build>

(Pick a <version> appropriate to your project.)

For Ant, the snippet below should help:

<jar destfile="build/main/checksites.jar">
  <fileset dir="build/main/classes"/>
  <zipfileset includes="**/*.class" src="lib/main/some.jar"/>
  <manifest>
    <attribute name="Main-Class" value="com.acme.checksites.Main"/>
  </manifest>
</jar>

Credits Michael Niemand -

For Gradle:

plugins {
    id 'java'
}

jar {
    manifest {
        attributes(
                'Main-Class': 'com.mypackage.MyClass'
        )
    }
}

Answer 13

That is because Java cannot find the Main attribute in the MANIFEST. MF file. The Main attribute is necessary to tell java which class it should use as the application's entry point. Inside the jar file, the MANIFEST. ... You get this "no main manifest attribute" error when this line is missing from the MANIFEST

When you run a self-executable jar, java will look for the Main-Class in MANIFEST. MF file located under the META-INF folder. If it is not able to find an entry, then it will complain about Unable to execute jar- file: “no main manifest attribute”.