I'm trying to understand how Scala code works with Java in Java's IDE. I got this doubt while working with Spark Java where I saw Scala packages too in code and using respective classes and methods.
My understanding says, Scala code need Scala's compiler to convert into Java.class files and then from their onwards JDK do its part in JVM to convert into binaries and do actions. Please correct me if am wrong.
After that, In my spark Java project in eclipse, I couldnt see anywhere where scala compiler is being pointed.
This is my pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>spark</groupId>
<artifactId>Project</artifactId>
<version>0.0.1-SNAPSHOT</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.4.0</version>
<relativePath />
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<!-- <exclusions> <exclusion> <groupId>ch.qos.logback</groupId> <artifactId>logback-classic</artifactId>
</exclusion> </exclusions> -->
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-core_2.12</artifactId>
<version>3.0.0</version>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-sql_2.12</artifactId>
<version>3.0.0</version>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-sql-kafka-0-10_2.12</artifactId>
<version>3.0.0</version>
</dependency>
<!-- Gson -->
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.8.6</version>
<scope>provided</scope>
</dependency>
<!-- Avro Messages -->
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-avro_2.12</artifactId>
<version>3.1.2</version>
</dependency>
<!-- Spark MLLIB -->
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-mllib_2.12</artifactId>
<version>3.0.0</version>
<scope>provided</scope>
</dependency>
<!-- https://mvnrepository.com/artifact/org.codehaus.janino/janino -->
<dependency>
<groupId>org.codehaus.janino</groupId>
<artifactId>commons-compiler</artifactId>
</dependency>
<dependency>
<groupId>org.codehaus.janino</groupId>
<artifactId>janino</artifactId>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<!--Spark java.lang.NoClassDefFoundError: org/codehaus/janino/InternalCompilerException -->
<dependency>
<groupId>org.codehaus.janino</groupId>
<artifactId>commons-compiler</artifactId>
<version>3.0.16</version>
</dependency>
<dependency>
<groupId>org.codehaus.janino</groupId>
<artifactId>janino</artifactId>
<version>3.0.16</version>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
And for example am using below import of scala in my Java class file. But literally not getting Idea from which Jars its picking and where its getting compiled to Java.class for further processing.
import scala.collection.JavaConverters;
Can anyone please help me to understand this unknown magic to me ?
Dependencies ship in class file form. That JavaConverters class must indeed be compiled by scalac. However, the maintainers of janino have done this on their hardware, shipped the compiled result to mavencentral's servers, which distributed it to all mirrors, which is how it ended up on your system's disk, which is why you do not need scalac to use it.
The jars, they have compiled files only. They will not have the source files. If you are using any dependency, it is not the source, it is compiled output. So, in your case, JavaConverters, is compiled too. And it is from the package scala.collection which is a built-in package.
May I know you have Scala installed on your system?
Related
I need to use BOMs in my project, so simplify the task of managing dependencies. This is the requirement, I cannot pivot at this stage.
I removed parent spring-boot and added AWS, Spring Boot and Junit5 as BOMs. The issue is, even though I have them, dependencies aren't downloaded correctly. Am I missing some plugins or I am doing something else wrong?
I have tried:
Run code without BOMs
Research BOM usage
Run project with parent of Spring Boot
Research similar projects on GitHub
All of the above worked correctly. The issues I am getting after adding BOMs are:
package org.junit.jupiter.api does not exist
package org.mockito does not exist
cannot find symbol
[ERROR] symbol: class ExtendWith
My pom.xml file:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.example</groupId>
<artifactId>bom-experiments</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<maven.compiler.source>11</maven.compiler.source>
<maven.compiler.target>11</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<junit-jupiter.version>5.7.2</junit-jupiter.version>
<aws-sdk.version>2.18.16</aws-sdk.version>
<mockito-inline.version>4.8.0</mockito-inline.version>
<org.springframework.boot.version>2.7.5</org.springframework.boot.version>
<org.springframework.version>5.3.24</org.springframework.version>
<lombok.version>1.18.24</lombok.version>
<maven-compiler-plugin.version>3.10.1</maven-compiler-plugin.version>
<maven-surefire-plugin.version>3.0.0-M7</maven-surefire-plugin.version>
<junit-jupiter-params.version>${junit-jupiter.version}</junit-jupiter-params.version>
<kubernetes-maven-plugin.version>1.9.0</kubernetes-maven-plugin.version>
<!-- Plugins -->
<mockito.version>4.9.0</mockito.version>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-framework-bom</artifactId>
<version>${org.springframework.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<version>${org.springframework.boot.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>software.amazon.awssdk</groupId>
<artifactId>bom</artifactId>
<version>${aws-sdk.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.junit</groupId>
<artifactId>junit-bom</artifactId>
<version>${junit-jupiter.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-bom</artifactId>
<version>${mockito.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<!-- Secret managers -->
<dependency>
<groupId>software.amazon.awssdk</groupId>
<artifactId>secretsmanager</artifactId>
</dependency>
<dependency>
<groupId>software.amazon.awssdk</groupId>
<artifactId>ssm</artifactId>
</dependency>
<dependency>
<groupId>software.amazon.awssdk</groupId>
<artifactId>sts</artifactId>
</dependency>
<!-- Lombok -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
<scope>provided</scope>
</dependency>
<!-- Testing -->
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-inline</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-junit-jupiter</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-params</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<finalName>bom-experiments</finalName>
<sourceDirectory>${project.basedir}</sourceDirectory>
<testSourceDirectory>${project.basedir}/src/test</testSourceDirectory>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>${maven-surefire-plugin.version}</version>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
</plugin>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>${org.springframework.boot.version}</version>
</plugin>
</plugins>
</build>
</project>
Am I understanding BOM concept wrong? Why are there no dependencies, even though they are declared in pom.xml? How can I run this code without parent but with BOM?
Importing the BOM via dependencyManagement and scope import copies their dependencyManagement configuration into your current dependencyManagement, as you would have written these dependencyManagement configuration.
The section dependencyManagement should only be used within POM of packaging pom. The resulting pom artefact could be used as parent of other POM.
Therefore you should not use BOM without parent.
Have a closer look at https://maven.apache.org/guides/introduction/introduction-to-dependency-mechanism.html
The issue I had, was related to a misconfiguration in pom.xml
Instead of
<sourceDirectory>${project.basedir}</sourceDirectory>
I have to use
<sourceDirectory>${project.basedir}/src/main</sourceDirectory>
This said, it is possible to package differently from pom packaging, so I can use jar or other alternatives.
I have a problem building the spring boot application. We need to build the project with the 'lib/bin/conf' structure using the maven. I did it with another project and there is no problem. But now, a conflict occurred and an action is recommended.
***************************
APPLICATION FAILED TO START
***************************
Description:
An attempt was made to call a method that does not exist. The attempt was made from the following location:
org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.<init>(DefaultSingletonBeanRegistry.java:88)
The following method did not exist:
'java.util.Map org.springframework.core.CollectionFactory.createConcurrentMapIfPossible(int)'
The calling method's class, org.springframework.beans.factory.support.DefaultSingletonBeanRegistry, is available from the following locations:
jar:file:/Users/user/.m2/repository/org/springframework/spring/2.5.5/spring-2.5.5.jar!/org/springframework/beans/factory/support/DefaultSingletonBeanRegistry.class
jar:file:/Users/user/.m2/repository/org/springframework/spring-beans/5.3.18/spring-beans-5.3.18.jar!/org/springframework/beans/factory/support/DefaultSingletonBeanRegistry.class
The calling method's class was loaded from the following location:
file:/Users/user/.m2/repository/org/springframework/spring/2.5.5/spring-2.5.5.jar
The called method's class, org.springframework.core.CollectionFactory, is available from the following locations:
jar:file:/Users/user/.m2/repository/org/springframework/spring-core/5.3.18/spring-core-5.3.18.jar!/org/springframework/core/CollectionFactory.class
jar:file:/Users/user/.m2/repository/org/springframework/spring/2.5.5/spring-2.5.5.jar!/org/springframework/core/CollectionFactory.class
The called method's class hierarchy was loaded from the following locations:
org.springframework.core.CollectionFactory: file:/Users/user/.m2/repository/org/springframework/spring-core/5.3.18/spring-core-5.3.18.jar
Action:
Correct the classpath of your application so that it contains compatible versions of the classes org.springframework.beans.factory.support.DefaultSingletonBeanRegistry and org.springframework.core.CollectionFactory
How can I solve this problem? Some of the libraries provided by the company have been deleted. This is my pom file.
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.6.6</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>...</groupId>
<artifactId>...</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>...</name>
<properties>
<java.version>11</java.version>
<finalName>${project.artifactId}-${project.version}</finalName>
<logback.version>1.2.9</logback.version>
<log4j.version>2.17.0</log4j.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-batch</artifactId>
</dependency>
<dependency>
<groupId>net.javacrumbs.shedlock</groupId>
<artifactId>shedlock-spring</artifactId>
<version>4.34.0</version>
</dependency>
<dependency>
<groupId>net.javacrumbs.shedlock</groupId>
<artifactId>shedlock-provider-jdbc-template</artifactId>
<version>4.34.0</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<!-- vault -->
<dependency>
<groupId>org.springframework.vault</groupId>
<artifactId>spring-vault-core</artifactId>
<version>2.2.2.RELEASE</version>
</dependency>
<!-- log4j -->
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-api</artifactId>
<version>${log4j.version}</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>${log4j.version}</version>
</dependency>
<!-- logback -->
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-core</artifactId>
<version>${logback.version}</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>${logback.version}</version>
</dependency>
<!-- Swagger 2 -->
<dependency>
<groupId>io.springfox</groupId>
<artifactId>springfox-swagger2</artifactId>
<version>2.9.2</version>
</dependency>
<dependency>
<groupId>io.springfox</groupId>
<artifactId>springfox-swagger-ui</artifactId>
<version>2.9.2</version>
</dependency>
<!-- Apache Commons -->
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.11</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.8.0</version>
</dependency>
<dependency>
<groupId>commons-beanutils</groupId>
<artifactId>commons-beanutils</artifactId>
<version>1.9.4</version>
</dependency>
<dependency>
<groupId>io.lettuce</groupId>
<artifactId>lettuce-core</artifactId>
<version>5.2.2.RELEASE</version>
</dependency>
<!--proxy-->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpcore</artifactId>
<version>4.4.13</version>
</dependency>
</dependencies>
<build>
<finalName>${finalName}</finalName>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<excludes>
<exclude>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</exclude>
</excludes>
</configuration>
</plugin>
</plugins>
</build>
</project>
Spring 2.5.5 has been obsolete for 12 years; there's no reason for you to have it. Furthermore, it makes absolutely no sense whatsoever to have a lib directory with Maven; dependency management is much of what Maven is for.
I see nothing in your POM that would pull in Spring 2.5.5. Is it possible that something else related to your project made a typo and intended to include Spring Boot 2.5.5? In any case, determine where this is coming from (mvn dependency:tree) and fix that.
DefaultSingletonBeanRegistry and CollectionFactory are duplicate in spring-2.5.5, actually they are already included in spring-beans and spring-core.
Execute 'mvn dependency:tree -Dverbose' to see how spring-2.5.5 is included, exclude it and try again
I am trying to access the Hive server present in GCP - Dataproc from my local machine(eclipse) using java and spark. But I am getting the below error while starting the application. I tried to find the problem but unable to solve it.
Exception in thread "main" java.lang.IllegalArgumentException: Unable to instantiate SparkSession with Hive support because Hive classes are not found.
at org.apache.spark.sql.SparkSession$Builder.enableHiveSupport(SparkSession.scala:870)
at com.hadoop.Application.main(Application.java:22)
Pom.xml:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.5.1</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.hadoop</groupId>
<artifactId>hadoop</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>hadoop</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>com.google.cloud</groupId>
<artifactId>libraries-bom</artifactId>
<version>20.6.0</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.google.cloud</groupId>
<artifactId>google-cloud-dataproc</artifactId>
<version>1.5.2</version>
</dependency>
<dependency>
<groupId>com.google.cloud</groupId>
<artifactId>google-cloud-storage</artifactId>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-core_2.11</artifactId>
<version>2.4.7</version>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-sql_2.11</artifactId>
<version>2.4.7</version>
<scope>provided</scope>
<exclusions>
<exclusion>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.47.Final</version>
</dependency>
<dependency>
<groupId>org.apache.hadoop</groupId>
<artifactId>hadoop-hdfs</artifactId>
<version>2.10.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-hive_2.11</artifactId>
<version>2.4.7</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>com.sun.jersey</groupId>
<artifactId>jersey-client</artifactId>
<version>1.9</version>
</dependency>
<dependency>
<groupId>org.objenesis</groupId>
<artifactId>objenesis</artifactId>
<version>2.5.1</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
The problem is with the scope of the following dependency:
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-hive_2.11</artifactId>
<version>2.4.7</version>
<scope>provided</scope>
</dependency>
According to the Maven doc:
compile: 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.
provided: This is much like compile, but indicates you expect the JDK or a container to provide the dependency at runtime. For example, when building a web application for the Java Enterprise Edition, you would set the dependency on the Servlet API and related Java EE APIs to scope provided because the web container provides those classes. A dependency with this scope is added to the classpath used for compilation and test, but not the runtime classpath. It is not transitive.
You might want to change it to compile or remove the line. Or download the jar and add it to the classpath.
Also see this doc on how to create a Spark application uber jar which includes its dependencies.
I moved some files into new packages so that things would make more sense, but this has resulted in my dependencies getting messed up.
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
These lines give "cannot resolve symbol 'springframework'" with the advice of adding a maven dependency. If I do this nothing changes within the pom.xml file. Also the pom has errors with "spring-boot-starter-frontData-jpa" and "org.springframework.frontData" saying dependency not found.
Everything worked fine before but is messed up now. I've tried invalidate & restart which doesn't solve anything, undoing the changes also doesn't seem to work. Does anyone have an idea on this? The pom.xml file can be found below. Also might be important I'm working on intellij.
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.3.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>be.uantwerpen.idlab.dust</groupId>
<artifactId>initializr</artifactId>
<version>0.1</version>
<name>dust-initializr</name>
<description></description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-frontData-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.frontData</groupId>
<artifactId>spring-frontData-rest-core</artifactId>
<version>3.1.5.RELEASE</version>
</dependency>
<dependency>
<groupId>com.googlecode.json-simple</groupId>
<artifactId>json-simple</artifactId>
<version>1.1.1</version>
</dependency>
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.8.5</version>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter</artifactId>
<version>RELEASE</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.ainslec</groupId>
<artifactId>picocog</artifactId>
<version>1.0.7</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<finalName>dust-initializr</finalName>
</configuration>
</plugin>
</plugins>
</build>
</project>
I've solved this by reverting changes through git.
Re-doing the moves didn't give the same error this time.
Not shure where this error came from and advice is welcome should it happen again.
I wrote this pom.xml based on an spring boot sample.
And when I started my app, I got this error:
SLF4J: Detected both log4j-over-slf4j.jar AND bound slf4j-log4j12.jar on the class path, preempting StackOverflowError.
I'm totally new to Java and Maven, and stuck here for quite a while.
I tried to wrote some exclusions in dependency. But it didn't work out. I have no idea which package should be excluded from which. If so, how can the package which is depended on, work normally?
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<!-- Your own application should inherit from spring-boot-starter-parent -->
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-samples</artifactId>
<version>2.0.0.BUILD-SNAPSHOT</version>
</parent>
<artifactId>spring-boot-sample-web-secure-jdbc</artifactId>
<name>Spring Boot Web Secure JDBC Sample</name>
<description>Spring Boot Web Secure JDBC Sample</description>
<url>http://projects.spring.io/spring-boot/</url>
<organization>
<name>Pivotal Software, Inc.</name>
<url>http://www.spring.io</url>
</organization>
<properties>
<main.basedir>${basedir}/../..</main.basedir>
</properties>
<dependencies>
<!-- Compile -->
<dependency>
<groupId>org.apache.hadoop</groupId>
<artifactId>hadoop-common</artifactId>
<version>3.0.0-alpha2</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-security</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
</dependency>
<!-- Test -->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
This happens because spring-boot-starter is pulling in the log4j-over-slf4j dependency, and one of your other dependencies is pulling in log4j.
run mvn dependency:tree and you should be able to find which dependency is pulling in the unwanted log4j and exclude it with
<exclusions>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
</exclusion>
<exclusion>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
</exclusion>
</exclusions>
It may only be one of those depending on what you see on thee mvn dependency:tree
If you would rather use log4j then obviously just exclude log4j-over-slf4j from spring-boot-starter instead.
This problem is due to the endless loop between logging facade and logging framework call.
https://www.slf4j.org/codes.html#log4jDelegationLoop
My scenario is slightly more complicate. Besides this loop problem. I have two logging framework.
I end up excluding log4j-over-slf4j and logback-classic.
I saw on your pom.xml there's no dependency for log4j. You should put this to your pom.xml:
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>