For example, if Main.class is in a package called foo the entry point can be specified in the following ways: If you look at the properties dialog for the project (from project tab, right click on your project and select properties) you'll see that there is a "run" item in the "Categories" window. If your jar's MANIFEST file doesn't contain "Main-Class" than you can not run Java program using the command "java -jar name.jar" , it will result in "Failed to load Main-Class manifest attribute from jar". My manifest shows like this: Manifest-Version: 1.0 Archiver-Version: Plexus Archiver Created-By: Apache Maven Built-By: dbell Build-Jdk: 1.7.0_05 It's being generated by the IDE though. When you run self-executable jar, java will look for the Main-Class in MANIFEST.MF file located under META-INF folder. Use it to specify the application entry point without editing or creating the manifest file. My above method works well. I used Eclipse's method today, but the Manifest is just one line and didn't specify the location of my Main class. For NetBeans specifically, Nate has posted the correct solution above. But in this case, since the file is from an application, i cannot do that. Right-click Project -> Export -> Java/JAR file, Next, JAR File Specification, Next, JAR Packaging Options, Next, JAR Manifest Specification. Below are the content of the POM.xml and Demo.java file. Wondering how you could look at what’s inside a jar file? com.company etc). Manifest files are text files. Initialization of an ArrayList in one line, 'Must Override a Superclass Method' Errors after importing a project into Eclipse. You need the maven-jar-plugin (see Maven's example). The default is to just generate a default manifest for the JAR, and not to save the generated file back to the project, so if you open up your JAR file, it will have a manifest, but it will just have something like: If you want to change your existing JARs without re-building them, the easiest way is probably to just do as mad-j suggested and open them with a Zip tool and edit the existing /META-INF/MANIFEST.MF file and save it back into the JAR. How to add local jar files to a Maven project? For IntelliJ, there is the post here. (dot) character as the delimiter. -Dev On. Are 4/8 in 60bpm and 4/4 in 120bpm the same? If you are using any IDE, there should be an option to export project as runnable jar, you can make use of that to let the IDE take care of correct manifest. Click on it and you'll see a dialog where you can specify the Main Class for the jar. part of the question. 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. I have not figured out how to make it add my Main class, so I created my own MANIFEST.MF file, added it to my project main directory (not src and not lib). Java will also throw Failed to load Main-Class manifest attribute from test.jar even if you have Main-Class attribute but not spelled correctly so watch out for spelling mistake there. It has a manifest option to specify all the attributes yo need to include. It only includes the line Manifest-Version: 1.0. What is the best way to remove 100% of a software that is not yet installed? It can be used while creating or updating a JAR file. Stack Overflow for Teams is a private, secure spot for you and The default is to just generate a default manifest for the JAR, and not to save the generated file back to the project, so if you open up your JAR file, it will have a manifest, but it will just have something like: This plugin will create the required entries that Rp has mentioned in the manifest file when the project is built. site design / logo © 2020 Stack Exchange Inc; user contributions licensed under cc by-sa. Use it to specify the application entry point without editing or creating the manifest file. I found that a method I was hoping to publish is already known. Is it too late for me to get into competitive chess? Also I have Maven 3 and I found some of the suggestions on the web don't match the maven code used with Netbeans as well. The Main attribute is necessary to tell java which class it should use as the application’s entry point. Can this be by chance? What LEGO piece is this arc with ball joint? Using Eclipse, on the JAR Manifest Specification page at the bottom, there is a text box where you can browse for your Main class. This doesn't work for signed JARs, of course. These type of problems are trivial but kills lot of time, just ensure your contents and location of the file is correct. Thanks for contributing an answer to Stack Overflow! I know this is an old question but in case it helps anyone. If it is not able to find an entry,then it will complain with Unable to execute jar- file: “no main manifest attribute”. site design / logo © 2020 Stack Exchange Inc; user contributions licensed under cc by-sa. your coworkers to find and share information. Is there any better way of creating a JAR file that has a Manifest? The 'e' flag (for 'entrypoint') creates or overrides the manifest's Main-Class attribute. This was the most helpful answer here and should IMO be the main answer of this post. Make sure the Manifest has the path to your Main class (e.g. While yours is a valid option, it doesn't exactly answer the "what's going on?" if I did? I mistakenly revealed name of new company to HR of current company. Why is it that the congruence relations usually correspond to some type of subobject? How can I deal with claims of technical difficulties for an online exam? your coworkers to find and share information. Meaning of the Term "Heavy Metals" in CofA? By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy. The default is to just generate a default manifest for the JAR, and not to save the generated file back to the project, so if you open up your JAR file, it will have a manifest, but it will just have something like: That should have been java -jar app.jar instead of java -jar "app".. The interesting bit is in the where we don't need to package the system stuff, and we want the dependant classes wrapped into our JAR. 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 eclipse, I haven't found any solution regarding this problem. Then, when I go to Export > JAR File, hit Next all the way to the end (do not hit Finish too early) and click the option to select manifest from project. Choosing THHN colors when running 2 circuits together, How can I perform discrete optimisation of a variable over a data set. A manifest is a simple text file, Sun's tutorial describes its contents in detail. Making statements based on opinion; back them up with references or personal experience. And then you can run jar command java -jar fileName.jar. Take time to understand ! Open the jar file with WinRAR. Eclipse provides options to generate a manifest file for the Jar, save that generated manifest into the project, or use a specified file for the manifest. Hope that saves you the few hours of checking and testing to make it happen. @Pete this doesn't work with Maven projects in NetBeans. Close Modal Dialog. This information was missing in the MANIFEST.MF.Below the content of this file before adding the maven-jar-plugin : Something like this: A default manifest file is created when you create a jar using jar cf jar-file inputs-files. If it’s not an executable JAR, then you’ll need to run the program with something like: You could just use this for command line: You wouldn't have to go into specifics of the Manifest file in this case. End of dialog window. I've researched on the Internet, but it seems different solutions for different IDEs. @adamdunson "What's going on" is directly related to which IDE is involved. How to add local jar files to a Maven project? MANIFEST.MF contains information about files contained in the Jar file. Since your are running an executable jar file, Java will look for the manifest MANIFEST.MF located under META-INF/ which contains information about the files packaged.. Java must know the main class to run. Use it to specify the application entry point without editing or creating the manifest file. How does the UK manage to transition leadership so quickly compared to the USA? Then re-build. It only works for projects managed by npproject. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. How can I deal with claims of technical difficulties for an online exam? Fix no main manifest attribute, in jar Error in Spring Boot Add spring-boot-maven-plugin in build section of your pom.xml. rev 2020.11.24.38066, Stack Overflow works best with JavaScript enabled, Where developers & technologists share private knowledge with coworkers, Programming & related technical career opportunities, Recruit tech talent & build your employer brand, Reach developers & technologists worldwide, I gave this a shot, trying java jar cfm testSql-1.0.jar Manifest.txt com/MyCompany/testsql/*.class and it returned the error "Could not find or load main class jar". If a piece of software does not specify whether it is licenced under GPL 3.0 "only" or "or-later", which variant does it "default to"? Thanks for contributing an answer to Stack Overflow! Take time to understand ! How can I create an executable JAR with dependencies using Maven? Inside the jar file, the MANIFEST.MF file is located in META-INF folder. This is done with the maven-dependency-plugin below. The main attribute inside the MANIFEST.MF looks like this: Main-Class: . You get this “no main … It can be used while creating or updating a JAR file. For example, this command creates app.jar where the Main-Class attribute value in the manifest is set to MyApp: By using our site, you acknowledge that you have read and understand our Cookie Policy, Privacy Policy, and our Terms of Service. I have been having this problem with Netbeans 8.0 and the built-in Maven project for the "Java Application" project prototype. That information will end up in your manifest. This information was missing in the MANIFEST.MF.Below the content of this file before adding the maven-jar-plugin : How does Linux retain control of the CPU on a single-core machine? You will see these used in the maven-jar-plugin. You need the version, otherwise, project doesn't build. Asking for help, clarification, or responding to other answers. Thanks that's a good point! I have tried adding a manifest.mf file specifying what main is, I've also been into project properties and added it as the main file... Hope there is a problem in your manifest file. Do you have an empty line at the end of the manifest file? The fully.qualified.MainClass starts at the package hierarchy. “No Main Manifest Attribute” in ----.jar Netbeans, How to write an effective developer resume: Advice from a hiring manager, Podcast 290: This computer science degree is brought to you by Big Tech, “Question closed” notifications experiment results and graduation, MAINTENANCE WARNING: Possible downtime early morning Dec 2/4/9 UTC (8:30PM…, Can't execute jar- file: “no main manifest attribute”. But in this case, since the file is from an application, i cannot do that. See Packaging Programs in JAR Files to learn how to create an executable JAR.. The other thing the built-in example prototype didn't do was to package my sub-projects into the JAR so I can run from the command line. Java Hungry As you can see that the ‘no main manifest attribute’ related error has been resolved and our application has given us the expected output. It can be used while creating or updating a JAR file. Using of the rocket propellant for engine cooling. rev 2020.11.24.38066, Stack Overflow works best with JavaScript enabled, Where developers & technologists share private knowledge with coworkers, Programming & related technical career opportunities, Recruit tech talent & build your employer brand, Reach developers & technologists worldwide. Asking for help, clarification, or responding to other answers. Example follows: This section tells Maven about the project. How do I legally resign in Germany when no one is at the office? What would be a proper way to retract emails sent to professors asking for help? For example, this command creates app.jar where the Main-Class attribute value in the manifest is set to MyApp: Could not figure out how to get Eclipse to do it, so I made my own Manifest file and selected it during Export in my Eclipse Project. Are broiler chickens injected with hormones in their left legs? Also, I left in some normal stuff to provide context. A tribute to "Most ways to uncheck the king", How to get an update of deleted file on host machine only with rsync. Why is it easier to carry a person while spinning than not spinning? Happy to ppoint to a correction if someone wants to post as an Answer here. For example this is how a basic Manifest file would look like: I tried @Michael's method but I ended up with no class files left in my JAR and only Manifest files.. oh well. I have Eclipse 3.4.2 and it's on the fourth screen in this process: Right-click Project -> Export -> Java/JAR file, Next, JAR File Specification, Next, JAR Packaging Options, Next, JAR Manifest Specification. Our projects use Gradle now days and I'm not in the loop. All you have to do is create such a file and update the JAR files with this command: With Ant you can use jar task. Limitations of Monte Carlo simulations in finance. For example, this command creates app.jar where the Main-Class attribute value in the manifest is set to MyApp: You can directly invoke this application by running the following command: If the entrypoint class name is in a package it may use a '.'