Develop Reference

Using Maven Dependency in RCP app and getting ClassNotFoundException from included dependency

I want to include XStream in my RCP project and used a Maven Dependency to add it to my target definition.
<location includeDependencyDepth="infinite" includeDependencyScopes="compile,provided,runtime,test,system,import" includeSource="true" missingManifest="generate" type="Maven">
<dependencies>
<dependency>
<groupId>com.thoughtworks.xstream</groupId>
<artifactId>xstream</artifactId>
<version>1.4.20</version>
<type>jar</type>
</dependency>
</dependencies>
</location>
From this diagram, it seems like xmlpull is present but XStream throws ClassNotFoundException in the constructor.
java.lang.ClassNotFoundException: org.xmlpull.v1.XmlPullParserException cannot be found by xstream_1.4.20
Looking more closely, I see that there are a number of new plugins named wrapped.bundlename. I then reconfigured the Maven Dependency to produce a feature and added the feature to my core feature.
The run configuration picked up the new feature but xmlpull was still not found at runtime. In desperation, I added all plugins (xmlpull included) to the run configuration but there was no improvement.
Is this the right approach for creating plugins from maven dependencies?

How to solve dependency problem in maven because of using different versions of same project

I have 4 modules in my project.
Module1 (i.e. com.assign.print:printlog.value:3.0.0-SNAPSHOT) has one class i.e. Foo.java, inside this class, on more class is there which is using com.print.assess: mns.pro:2.0
Module2 , Module2 and Module4 are using com.print.assess: mns.pro:6.2.
In my project main pom.xml, the dependency is added as :
<dependency>
<groupId>com.print.assess</groupId>
<artifactId>mns.pro</artifaxtId>
<version>6.2</version>
</dependency>
In Foo.java, I have one class as DataVal.java which is using older version.
If I don't add
<dependency>
<groupId>com.print.assess</groupId>
<artifactId>mns.pro</artifaxtId>
<version>2.0</version>
</dependency>
to Module1 pom.xml, Redline error is coming for DataVal.java saying "cannot resolve the symbol". So when I added the dependency with version 2.0, the error was resolved but while installing project:
Failed while enforcing releasability the error(s) are [
Dependency convergence error for com.print.assess:mns.pro:6.2 paths to
dependency are:
+-com.assign.print:printlog.value:3.0.0-SNAPSHOT
+-com.app.print:print.sal:1.1.3
+-com.print.assess:mns.pro:6.2
and
+-com.assign.print:printlog.value:3.0.0-SNAPSHOT
+-com.print.assess:mns.pro:2.0
and
+-com.assign.print:printlog.value:3.0.0-SNAPSHOT
+-com.print.assess.over:multi-task.rev:3.1
+-com.print.assess:mns.pro:6.2
How to resolve this issue?
Thanks in advance

If you have the dependencyConvergence enforcer rule active (which you obviously have), you need to determine your versions in the <dependencyManagement> (which is different from the standard <dependencies>).
Then you can declare the dependencies without version in <dependencies>. dependencyManagement entries can be in the main pom and in modules as well. #Bahmut gave you the link to understand dependencyManagement.

You may want to move your 6.2 dependency in your main pom to <dependencyManagement> so it does not get imported by default. Then you can simply import the 6.2 version in your module poms like this:
<dependency>
<groupId>com.print.assess</groupId>
<artifactId>mns.pro</artifaxtId>
</dependency>
and in the module where you need version 2, you can import it like this:
<dependency>
<groupId>com.print.assess</groupId>
<artifactId>mns.pro</artifaxtId>
<version>2.0</version>
</dependency>
More information about dependency management can be found here:
https://maven.apache.org/guides/introduction/introduction-to-dependency-mechanism.html

Maven dependency weird bug

I have 4 projects in my eclipse workspace. They are all 4 maven projects. The names are API, Games, Faction, Board.
API is used in all the other maven projects (Games, Faction, Board) and itself depends of a jar into my PC and also HikariCP.
I declare this dependencies in my API pom.xml
<dependency>
<groupId>org.github.paperspigot</groupId>
<artifactId>paperspigot-api</artifactId>
<version>1.7.10-R0.1-SNAPSHOT</version>
<scope>system</scope>
<systemPath>${basedir}\lib\paperspigot-1.7.10-R0.1-SNAPSHOT.jar</systemPath>
</dependency>
<dependency>
<groupId>com.zaxxer</groupId>
<artifactId>HikariCP</artifactId>
<version>2.7.8</version>
<scope>compile</scope>
</dependency>
Then I declare on my 3 other projects that they depend of API
<dependency>
<groupId>net.onima</groupId>
<artifactId>onimaapi</artifactId>
<version>0.0.1-SNAPSHOT</version>
<scope>compile</scope>
</dependency>
But I have a big warning on the API and the error log says this:
I don't understand why is there this error as I can code with the API in my classes. Can someone explain me? Thanks
EDIT: As requested the text of the screenshot:
Description Resource Path Location Type
Project 'OnimaAPI' is missing required Java project: 'paperspigot' OnimaAPI Build path Build Path Problem
Description Resource Path Location Type
Project 'OnimaGames' is missing required Java project: 'onimaapi' OnimaGames Build path Build Path Problem
I don't know why I can't set the pom.xml here so here's a link: https://ghostbin.com/paste/r4u62

You're declaring paperspigot with system scope.
<dependency>
<groupId>org.github.paperspigot</groupId>
<artifactId>paperspigot-api</artifactId>
<version>1.7.10-R0.1-SNAPSHOT</version>
<scope>system</scope>
<systemPath>${basedir}\lib\paperspigot-1.7.10-R0.1-SNAPSHOT.jar</systemPath>
</dependency>
Dependencies with the scope system are always available and are not looked up in repository. They are usually used to tell Maven about dependencies which are provided by the JDK or the VM.
https://maven.apache.org/guides/introduction/introduction-to-dependency-mechanism.html#System_Dependencies
You should declare it with compile scope:
This is the default scope, used if none is specified. Compile dependencies are available in all classpaths of a project. Furthermore, those dependencies are propagated to dependent projects.

Deploy Spring boot gradle app in Google App Engine

I have searched for the tutorial to deploy Spring boot application using Gradle. I failed to find any resource that explains the process to do so.
Can anyone guide me the process?
My project works like a charm when its run locally on my machine. But I would like to deploy on the Google app engine's Flexible Java Environment.
Thanks, in advance.
My build.gradle looks like this
buildscript {
ext {
springBootVersion = '2.0.4.RELEASE'
jwtVersion = '3.4.0'
appEngineVersion = '1.9.56'
appEngineGradleToolsVersion = '1.3.4'
}
repositories {
mavenCentral()
}
dependencies {
classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
}
}
apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'idea'
apply plugin: 'org.springframework.boot'
apply plugin: 'io.spring.dependency-management'
group = 'com.example'
version = '0.0.1'
sourceCompatibility = 1.8
repositories {
mavenCentral()
}
dependencies {
compile('org.springframework.boot:spring-boot-starter-actuator')
compile('org.springframework.boot:spring-boot-starter-web')
compile('org.springframework.boot:spring-boot-starter-thymeleaf')
compile("org.springframework.boot:spring-boot-starter-security")
// JPA Data (We are going to use Repositories, Entities, Hibernate, etc...)
compile 'org.springframework.boot:spring-boot-starter-data-jpa'
// Use MySQL Connector-J
compile 'mysql:mysql-connector-java'
implementation "com.auth0:java-jwt:${jwtVersion}"
runtime('org.springframework.boot:spring-boot-devtools')
testCompile('org.springframework.boot:spring-boot-starter-test')
}

Spring Boot for Google App Engine Standard (Java 8)
This sample demonstrates how to deploy a Spring Boot application on Google App Engine.
See the Google App Engine standard - documentation for more detailed instructions.
See the Using Cloud SQL for MySQL for working with mysql
Java 8
Maven (at least 3.5)
Google Cloud SDK (aka gcloud command line tool)
Setup
Download and initialize the Cloud SDK
gcloud init
Create an App Engine app within the current Google Cloud Project
gcloud app create
Maven
Running locally
mvn appengine:run
To use vist: http://localhost:8080/
Deploying
mvn appengine:deploy
To use vist: https://YOUR-PROJECT-ID.appspot.com
Testing
mvn verify
As you add / modify the source code (src/main/java/...) it's very useful to add unit testing
to (src/main/test/...). The following resources are quite useful:
Junit4
Mockito
Truth
For further information, consult the
Java App Engine documentation.
Steps to convert a Spring Boot application for App Engine Standard
Use the WAR packaging
You must use WAR packaging to deploy into Google App Engine Standard.
If you generate a Spring Boot project from start.spring.io,
make sure you switch to the full version view of the initializer site, and select WAR
packaging.
If you have an existing JAR packaging project, you can convert it into a WAR project by:
1. In pom.xml, change <packaging>jar</packaging> to <packaging>war</packaging>
1. Create a new SpringBootServletInitializer implementation:
public class ServletInitializer extends SpringBootServletInitializer {
#Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
return application.sources(YourApplication.class);
}
}
Remove Tomcat Starter
Google App Engine Standard deploys your WAR into a Jetty server. Spring Boot's starter
includes Tomcat by default. This will introduce conflicts. Exclude Tomcat dependencies:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</exclusion>
</exclusions>
</dependency>
Do not include the Jetty dependencies. But you must include Servlet API dependency:
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
<scope>provided</scope>
</dependency>
Add App Engine Standard Plugin
In the pom.xml, add the App Engine Standard plugin:
<plugin>
<groupId>com.google.cloud.tools</groupId>
<artifactId>appengine-maven-plugin</artifactId>
<version>1.3.1</version>
</plugin>
This plugin is used to run local development server as well as deploying the application
into Google App Engine.
Add App Engine Configuration
Add a src/main/webapp/WEB-INF/appengine-web.xml:
<appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
<version>1</version>
<threadsafe>true</threadsafe>
<runtime>java8</runtime>
</appengine-web-app>
This configure is required for applications running in Google App Engine.
Exclude JUL to SLF4J Bridge
Spring Boot's default logging bridge conflicts with Jetty's logging system.
To be able to capture the Spring Boot startup logs, you need to exclude
org.slf4j:jul-to-slf4j dependency. The easiest way to do this is to
set the dependency scope to provided, so that it won't be included in
the WAR file:
<!-- Exclude any jul-to-slf4j -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jul-to-slf4j</artifactId>
<scope>provided</scope>
</dependency>
Out of memory errors
With Spring Boot >= 1.5.6, you may run into out of memory errors on startup.
Please follow these instructions to work around this issue:
Inside src/main/resources, adding a logging.properties file with:
.level = INFO
Inside src/main/webapp/WEB-INF/appengine-web.xml, add a config that points to the new logging.properties file.
<system-properties>
<property name="java.util.logging.config.file" value="WEB-INF/classes/logging.properties"/>
</system-properties>

maven dependency + local jar in build path = slf4j conflict

I try to use the IMPINJ Octane SDK Java which comes as a jar including all needed dependencies together with Spark Framework in a maven project. To include the Spark Framework I use maven and the Octane SDK jar is added to the build path. My pom.xml has only the spark dependency:
<dependency>
<groupId>com.sparkjava</groupId>
<artifactId>spark-core</artifactId>
<version>2.5</version>
</dependency>
Every time I try to run the program I get to following error.
Exception in thread "Thread-1" java.lang.NoSuchMethodError: org.slf4j.helpers.MessageFormatter.arrayFormat(Ljava/lang/String;[Ljava/lang/Object;)Lorg/slf4j/helpers/FormattingTuple;
at org.eclipse.jetty.util.log.JettyAwareLogger.log(JettyAwareLogger.java:619)
at org.eclipse.jetty.util.log.JettyAwareLogger.info(JettyAwareLogger.java:314)
at org.eclipse.jetty.util.log.Slf4jLog.info(Slf4jLog.java:74)
at org.eclipse.jetty.util.log.Log.initialized(Log.java:186)
at org.eclipse.jetty.util.log.Log.getLogger(Log.java:298)
at org.eclipse.jetty.util.log.Log.getLogger(Log.java:288)
at org.eclipse.jetty.util.component.AbstractLifeCycle.<clinit>(AbstractLifeCycle.java:35)
at spark.embeddedserver.jetty.EmbeddedJettyFactory.create(EmbeddedJettyFactory.java:34)
at spark.embeddedserver.EmbeddedServers.create(EmbeddedServers.java:57)
at spark.Service.lambda$init$0(Service.java:342)
at java.lang.Thread.run(Thread.java:745)
The Octane SDK comes with slf4j and the Spark Framework also has slf4j as a dependency but they have different versions. I found the following thread NoSuchMethodError with SLF4J API but since I could remove slf4j from the jar I can't resolve the problem. How can I get this working?
I also tried to exclude slf4j in the pom but it did not work either:
<dependency>
<groupId>com.sparkjava</groupId>
<artifactId>spark-core</artifactId>
<version>2.5</version>
<exclusions>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
</exclusion>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
</exclusion>
</exclusions>
</dependency>
EDIT (SOLUTION):
I extracted the Octane SDK jar, removed slf4j and compressed it back to a jar.

My understanding is that sparks requires slf4j 1.7.13.
Then, you add Octane to the classpath (not through a maven dependency) and this Octane jar contains older classes of slf4j.
I just downloaded Octane to see for myself. I notice it include 2 versions:
OctaneSDKJava-1.22.0.30.jar
OctaneSDKJava-1.22.0.30-jar-with-dependencies.jar
You need to use OctaneSDKJava-1.22.0.30.jar and manually include all other dependencies but NOT the slf4j one (or the opposite, use OctaneSDKJava-1.22.0.30-jar-with-dependencies.jar and remove slf4j).
EDIT to answer a question in the comments:
I opened the latest OctaneSDKJava-1.26.2.0-jar-with-dependencies.zip, which contains a README.txt with the following details:
DEPENDENCIES
RUNTIME DEPENDENCIES
jdom 1.0 http://www.jdom.org
log4j 1.2.15 http://logging.apache.org/log4j/1.2/download.html
jargs 1.0 http://sourceforge.net/project/showfiles.php?group_id=33024
mina 1.1.7 http://mina.apache.org
slf4j-log4j12 1.5.0 http://www.slf4j.org
slf4j-api 1.5.0 http://www.slf4j.org
xerces-j 2.4.0 http://xerces.apache.org/
COMPILE DEPENDENCIES
velocity-dep 1.5 http://velocity.apache.org
jalopy 0.3.1 http://jalopy.sourceforge.net
jdom 1.0 http://www.jdom.org
log4j 1.2.15 http://logging.apache.org/log4j/1.2/download.html
commons-collection 3.2 http://commons.apache.org
commons-configuration 1.5 http://commons.apache.org
commons-lang 2.3 http://commons.apache.org
common-logging 1.1.1 http://commons.apache.org
JAXB RI dependencies including:
jaxb-xjc 2.0 https://jaxb.dev.java.net/
jaxb-impl 2.0 https://jaxb.dev.java.net/
jaxb-api 2.0 https://jaxb.dev.java.net/
activation 2.0 https://jaxb.dev.java.net/
jsr173_1.0_api 2.0 https://jaxb.dev.java.net/
The five above jaxb dependencies are available in a single jar "JAXB
RI" from https://jaxb.dev.java.net/. Execute this jar (doubleclick
windows, "java -jar " all other platforms) and copy the
individual jars to the LTKJava/lib directory) plus above runtime
dependencies
TEST DEPENDENCIES
JUnit 4.4 http://sourceforge.net/project/showfiles.php?group_id=15278
plus above dependencies note that the junit dependency needs to be
placed in the ANT_HOME/lib directory