Develop Reference

ClassNotFoundException while running gradle based Java Application in cmd

I have a Simple Gradle based Java project, After gradle build jar has been created under build/libs folder. When i try to run in cmd using java -jar discord-notification-bot-1.0-SNAPSHOT.jar in the below path
F:\github projects\discord-notification-bot\build\libs>
I'm getting below Error
Exception in thread "main" java.lang.NoClassDefFoundError: org/javacord/api/DiscordApiBuilder
at Application.main(Application.java:8)
Caused by: java.lang.ClassNotFoundException: org.javacord.api.DiscordApiBuilder
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 1 more
build.gradle
plugins {
id 'java'
}
group 'org.test'
version '1.0-SNAPSHOT'
repositories {
mavenCentral()
}
dependencies {
implementation 'org.javacord:javacord:3.0.6'
}
jar {
manifest {
attributes(
'Main-Class': 'Application'
)
}
}
under src/Application.java
import org.javacord.api.DiscordApi;
import org.javacord.api.DiscordApiBuilder;
public class Application {
public static void main(String[] args) {
String key = System.getenv().get("key");
DiscordApi api = new DiscordApiBuilder().setToken(key).login().join();
System.out.println("you can invite the bot by using following url "+api.createBotInvite());
}
}
It seems javacord library is not getting reflected while i run via cmd.
Note: in MANIFEST.MF I have main application correctly.
But dependency is not getting reflected while running via cmd.
So, What should I do for that?

The gradle java plugin will not add classpath information to the generated JARs by default. You could add this information similar to the way you added the main class but you're probably better off using the gradle application plugin.
With the application plugin you'll get an archive file as output that bundles all dependencies and some bat/sh files as well for execution. A simple gradle file with the application plugin might look like this:
plugins {
// Apply the application plugin to add support for building a CLI application in Java.
id 'application'
}
repositories {
// Use JCenter for resolving dependencies.
jcenter()
}
dependencies {
// This dependency is used by the application.
implementation 'com.google.guava:guava:29.0-jre'
}
application {
// Define the main class for the application.
mainClass = 'gradle.application.App'
}
As mentioned in the comments another solution might be to create a shadow/fat/uber-jar using the com.github.johnrengelman.shadow plugin. Which will result in this basic gradle file:
plugins {
id 'java'
// Apply the shadow plugin to add support for building a shadow-jar
id "com.github.johnrengelman.shadow" version "6.1.0"
}
repositories {
// Use JCenter for resolving dependencies.
jcenter()
}
dependencies {
// This dependency is used by the application.
implementation 'com.google.guava:guava:29.0-jre'
}
jar {
manifest {
attributes(
'Main-Class': 'Application'
)
}
}
With the shadow-plugin you get an additional task shadowJar that will create a JAR with all dependencies included. While this sounds very handy, it comes with some drawbacks e.g. when using the shadow-jar as dependency itself, which might result in the need of additional configuration. In your case however, this might be the best option.

Unable to build gradle project in eclipse?

After cleaning when i try to build gradle i get an error in the console saying:
package org.json does not exist import org.json.JSONObject;
cannot find symbol
symbol : class JSONObject
there are red marks in the java file at all places where jsonobject and json array exists.
I have put the folder web inf/lib that contains all the jar files inside the src/main/webapp directory that i have created.
currently the contents of my build.gradle file are:
/*
* This build file was auto generated by running the Gradle 'init' task
* by 'i2cdev001' at '14/11/18 3:11 PM' with Gradle 2.14.1
*
* This generated file contains a sample Java project to get you started.
* For more details take a look at the Java Quickstart chapter in the Gradle
* user guide available at https://docs.gradle.org/2.14.1/userguide/tutorial_java_projects.html
*/
// Apply the java plugin to add support for Java
apply plugin: 'java'
apply plugin: 'war'
// In this section you declare where to find the dependencies of your project
repositories {
// Use 'jcenter' for resolving your dependencies.
// You can declare any Maven/Ivy/file repository here.
jcenter()
}
// In this section you declare the dependencies for your production and test code
dependencies {
// The production code uses the SLF4J logging API at compile time
compile 'org.slf4j:slf4j-api:1.7.21'
// Declare the dependency for your favourite test framework you want to use in your tests.
// TestNG is also supported by the Gradle Test task. Just change the
// testCompile dependency to testCompile 'org.testng:testng:6.8.1' and add
// 'test.useTestNG()' to your build script.
testCompile 'junit:junit:4.12'
}
Note: Also in the project properties i am unable to see any jar files under the Web App Libraries in the java build path tab. I can see only access rules:no rules defined and native library locations:(none)

As your project is gradle project, Adding jar manually wont work.. You have to mention path where you have kept all your jar files in your build.gradle file.
Mention your jar file path in repository under flatDir {}:
repositories {
jcenter()
flatDir {
dirs 'libs'
}
}
Then you have to add which jar from that folder you have mentioned above (ie libs)
dependencies {
compile 'gson-0.1.0'
}

Spring Boot + Gradle: how to build executable jar

I'm trying to build an executable jar in Spring Boot + Gradle project, but for now nothing works. Here is the simplest possible structure. Possibly, something is missing in Gradle configuration.
Gradle:
buildscript {
ext {
springBootVersion = '1.5.8.RELEASE'
}
repositories {
mavenCentral()
}
dependencies {
classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
}
}
apply plugin: 'java'
apply plugin: 'org.springframework.boot'
group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = 1.8
repositories {
mavenCentral()
}
jar {
manifest {
attributes 'Main-Class': 'com.example.demo.DemoApplication'
}
from { configurations.compile.collect { it.isDirectory() ? it : zipTree(it) } }
}
dependencies {
compile('org.springframework.boot:spring-boot-starter-web')
}
Main config file:
#RestController
#SpringBootApplication
public class DemoApplication {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
#GetMapping(value = "/")
public String index() {
return "index";
}
}
When I ran the jar file like java -jar 1.jar, I got this exception:
[main] ERROR org.springframework.boot.SpringApplication - Applicati
on startup failed
org.springframework.beans.factory.BeanDefinitionStoreException: Failed to proces
s import candidates for configuration class [com.example.demo.DemoApplication];
nested exception is java.lang.IllegalArgumentException: No auto configuration cl
asses found in META-INF/spring.factories. If you are using a custom packaging, m
ake sure that file is correct.
at org.springframework.context.annotation.ConfigurationClassParser.proce
ssDeferredImportSelectors(ConfigurationClassParser.java:556)
at org.springframework.context.annotation.ConfigurationClassParser.parse
(ConfigurationClassParser.java:185)
at org.springframework.context.annotation.ConfigurationClassPostProcesso
r.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:308)
at org.springframework.context.annotation.ConfigurationClassPostProcesso
r.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:228)
at org.springframework.context.support.PostProcessorRegistrationDelegate
.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.ja
va:272)
at org.springframework.context.support.PostProcessorRegistrationDelegate
.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:92)
at org.springframework.context.support.AbstractApplicationContext.invoke
BeanFactoryPostProcessors(AbstractApplicationContext.java:687)
at org.springframework.context.support.AbstractApplicationContext.refres
h(AbstractApplicationContext.java:525)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationConte
xt.refresh(EmbeddedWebApplicationContext.java:122)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.
java:693)
at org.springframework.boot.SpringApplication.refreshContext(SpringAppli
cation.java:360)
at org.springframework.boot.SpringApplication.run(SpringApplication.java
:303)
at org.springframework.boot.SpringApplication.run(SpringApplication.java
:1118)
at org.springframework.boot.SpringApplication.run(SpringApplication.java
:1107)
at com.example.demo.DemoApplication.main(DemoApplication.java:13)
Caused by: java.lang.IllegalArgumentException: No auto configuration classes fou
nd in META-INF/spring.factories. If you are using a custom packaging, make sure
that file is correct.
at org.springframework.util.Assert.notEmpty(Assert.java:277)
at org.springframework.boot.autoconfigure.AutoConfigurationImportSelecto
r.getCandidateConfigurations(AutoConfigurationImportSelector.java:153)
at org.springframework.boot.autoconfigure.AutoConfigurationImportSelecto
r.selectImports(AutoConfigurationImportSelector.java:95)
at org.springframework.context.annotation.ConfigurationClassParser.proce
ssDeferredImportSelectors(ConfigurationClassParser.java:547)
... 14 common frames omitted
What might be wrong?

In Boot 2.x, the bootJar and bootWar tasks are responsible for packaging the application.
The bootJar task is responsible for creating the executable jar file. This is created automatically once the java plugin is applied.
In case the executable jar/war file is not generated run the below gradle task manually.
$./gradlew bootJar
Similarly, bootWar generates an executable war file and gets created once the war plugin is applied.
We can execute the bootWar task using:
$./gradlew bootWar
Note that for Spring Boot 2.x, we need to use Gradle 4.0 or later.

I created a project with all the sources you provided. Running "gradle build" from terminal, switching to /build/libs and then running "java -jar artifactname" works just fine.
Have you tried to clean and recompile? Which Version of Gradle are you using?

In spring boot you can directly create executable jar file by
springBoot {
executable = true
}
Please try
jar{
baseName = 'myapp'
version = 'version'
}
It will create jar with name myapp-version.jar
Do ./myapp-version.jar from command line.it will execute
Refer following link for more info. https://docs.spring.io/spring-boot/docs/current/reference/html/deployment-install.html

I just recently tried a Spring boot application with 2.1.4.Release with Gradle build.
I ran the following command from the directory in Windows CMD.
gradlew clean build
(upon required JDK8 installed in the system), I was able to see the JAR generated under,
<project-directory>/build/libs/<project-name-version.jar>
Hope this helps though older question.
Reference:

My two cents.
When using spring-boot if you want to customize the MANIFEST.MF file, you need to set the bootJar task, it won't work on the default jar task.
bootJar {
manifest {
attributes 'Start-Class': 'com.baeldung.DemoApplication'
}
}
https://www.baeldung.com/spring-boot-main-class

If you're trying to make your .jar file executable, for use such as in a systemd service. You'll have to edit the bootJar task and enable launchScript.
build.gradle
bootJar {
launchScript()
}
or with Gradle Kotlin DSL build.gradle.kts
tasks {
bootJar {
launchScript()
}
}
You should now be able to run your project's .jar file as an executable.

gradle project: error couldn't find main class

I have the following project structure:
Root project 'rmi-tutorial'
+--- Project ':client'
+--- Project ':lib'
\--- Project ':server'
The path to clients main class looks like this:
client/src/main/java/client/ComputePi.java
my build.gradle for the client subproject loooks like this:
dependencies {
compile project(':lib')
}
mainClassName = "ComputePi"
The main build.gradle file is this one:
subprojects {
apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'application'
repositories {
mavenCentral()
}
dependencies {
//compile project(':server')
//compile project(':client')
testCompile 'junit:junit:4.12'
}
version = '1.0'
jar {
manifest.attributes provider: 'gradle'
}
}
The generation of the jars works so far but the MANIFEST.MF file in the jar is wrong. It contains the following:
Manifest-Version: 1.0
provider: gradle
Where is my specified main class? When I try to execute the startscript that got created by the gradle application-plugin I get the error: couldn't find nor load main class
The jar contains all necessary class files

The application plugin does not produce a runnable JAR with Main-Class entry. Instead it generates a distribution with Windows and *nix start scripts where the main class is used and all libaries put to the class path.
If you want a runnable JAR, you have to configure it yourself, or use one of the plugins that produces a fat JAR, also including the dependencies into the runnable JAR (I don't like this, but it works if the target computer has the correct file associations set). If the target computer e. g. has associated JAR files with an archiving tool, double-clicking the JAR will open the JAR in the archiving tool, not run your application.
If you want to run your application, use gradlew run, or do gradlew installDist and then execute the application that is installed to build/install/.... That is how the application plugin works. With gradlew distZip or gradlew distTar you can create shippable archives of your application.

How to export a Spring Boot project to an executable standalone file?

I have created a project in Spring Tool Suite with Spring Boot and Gradle, and I really don't know how to export to make it work.
I don't know much about gradle, just the basics to add dependencies from the maven repository. So in some articles says to apply the application plugin to do the task, but I don't know how to set up the configuration file and how to create the executable.
If anyone could write or link a step by step detailed explanation on how to do it, it would be very much appreciated.
This is my build.gradle file:
buildscript {
repositories {
mavenCentral()
}
dependencies {
classpath("org.springframework.boot:spring-boot-gradle-plugin:1.3.1.RELEASE")
}
}
apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'spring-boot'
springBoot {
mainClass = "com.rodamientosbulnes.objetivosventa.Application"
executable = true
}
jar {
baseName = 'objetivosventa'
version = '0.1.0'
}
repositories {
mavenCentral()
}
sourceCompatibility = 1.8
targetCompatibility = 1.8
dependencies {
compile('org.springframework.boot:spring-boot-starter')
compile('org.springframework:spring-jdbc')
compile('net.sourceforge.jtds:jtds:1.3.1')
compile('org.apache.poi:poi-ooxml:3.13')
compile('com.miglayout:miglayout-swing:4.2')
}
task wrapper(type: Wrapper) {
gradleVersion = '2.3'
}

Build file looks fine, you only need to run gradle build (or Run As -> Gradle -> Gradle build in the STS) to create the runnable jar.
More details about configuration of the gradle plugin are available on spring boot documentation site.

Gradle's application plugin doesn't make a single execitable for you, but it can create a distribution, which includes all the dependencies, jar-artifact for your project and 2 scripts to run it (one batch-file and linex executable).
The main thing you need to know, is that spring-boot plugin already provide all the task from application plugin you may need. All the task you can find here. You need distZip or installDist to package your project to the distribution. This task will create a ready project distribution under your project-folder/build folder. One more task you may find usefull is buildRun which will run you spring-boot application without package it into distribution.