Java – gradle output jar does not have a main class

I have the following simple build Gradle file:

apply plugin: 'application'
apply plugin: 'java'

mainClassName = 'com.kurtis.HelloGradle'

The following individual java files are located in Src / main / Java / COM / kurtis / hellogradle java：

package com.kurtis;

public class HelloGradle {

    public static void main(String[] args) {

        System.out.println("Hello gradle");
    }

}

However, if I run the gradle build, I will get a jar without the main class setting in the build / lib directory Its manifest file does not have a main class entry Why?

Solution

This is due to the way the application plug - in works Mainclassname is an attribute used by the application plug-in. When it creates an executable jar, it does not need to have a main class in the list because it does not use it

If you need to have a main class in your jar, you must provide its vie jar configuration with the Java plug-in, as shown below:

jar {
  manifest {
    attributes(
      'Main-Class': 'com.kurtis.HelloGradle'
    )
  }
}

Otherwise, just use the executable generated by the application plug-in, whether by running the task or through the distribution it can create for you, and use the script to run the application and all its dependencies