Guide for Supporting Multiple Versions of Java (8, 11, 14) in Your Maven Project
In this article, see a guide for supporting multiple versions of Java in your Maven project.
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Join For FreeThe new version of Java is here! But you cannot migrate at this moment, that is not a problem, because you can do it partially.
If this is you problem, then you are in right place. :)
In this article, you will see how to support multiple versions of Java in a Maven project.
Prerequisites
- Installed Maven
- Installed multiple versions of Java
Steps for Supporting Multiple Java Versions
- Create toolchains.xml file
- Possible locations for toolchains.xml
- Add Maven Toolchains dependency in parent .pom
- Add configuration for specific JDK version in modules
- First module, use the feature from JDK 8 and simple JUnit test
- Second module, use the feature from JDK 11 and simple JUnit test
- Third module, use the feature from JDK 14 and simple JUnit test
- Execute 'mvn clean install' and check logs
- Check Java 14 features in IntelliJ
- Source code for this example
Install Maven
Start by updating the package index:
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sudo apt update
Next, install Maven by typing the following command:
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sudo apt install maven
Verify the installation by running the mvn -version command:
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mvn -version
Install Multiple Java Versions
First, update the apt package index with:
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sudo apt update
Once the package index is updated install the default Java OpenJDK package with:
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sudo apt install default-jdk
Verify the installation, by running the following command which will print the Java version:
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java -version
The output will look something like this:
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openjdk version "11.0.2" 2019-01-15
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OpenJDK Runtime Environment (build 11.0.2+9-Ubuntu-3ubuntu118.04.3)
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OpenJDK 64-Bit Server VM (build 11.0.2+9-Ubuntu-3ubuntu118.04.3, mixed mode, sharing)
Note: Repeat process for all versions of Java, which are required for your specific case.
Steps for Supporting Multiple Java Versions
Create toolchains.xml file
This file will be used in 'maven-toolchains-plugin' and whole configuration for jdk version should be in this file.
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<toolchains>
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<!-- JDK toolchains -->
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<toolchain>
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<type>jdk</type>
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<provides>
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<version>8</version>
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</provides>
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<configuration>
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<jdkHome>/usr/lib/jvm/java-8-openjdk-amd64/jre</jdkHome>
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</configuration>
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</toolchain>
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<toolchain>
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<type>jdk</type>
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<provides>
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<version>11</version>
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</provides>
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<configuration>
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<jdkHome>/home/sasa/Downloads/jdk11/amazon-corretto-11.0.6.10.1-linux-x64</jdkHome>
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</configuration>
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</toolchain>
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<toolchain>
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<type>jdk</type>
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<provides>
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<version>14</version>
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</provides>
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<configuration>
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<jdkHome>/home/sasa/Downloads/jdk11/jdk-14</jdkHome>
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</configuration>
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</toolchain>
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<!-- other toolchains -->
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</toolchains>
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Possible Locations for toolchains.xml
Case 1: This file can be located in your ~/.m2 when configuration is user based
Case 2: This file can be located in {maven_home}/conf
Case 3: Can be added as parameter while executing maven command
Add Maven Toolchains Dependency in parent .pom
Parent pom in this example looks like:
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<groupId>com.sasa.multipleversions.examples</groupId>
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<artifactId>multiple-java-versions</artifactId>
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<version>1.0.0</version>
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<packaging>pom</packaging>
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<modules>
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<module>module-jdk-8</module>
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<module>module-jdk-11</module>
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<module>module-jdk-14</module>
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</modules>
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<build>
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<plugins>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-compiler-plugin</artifactId>
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<version>3.8.1</version>
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</plugin>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-surefire-plugin</artifactId>
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<version>3.0.0-M4</version>
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</plugin>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-toolchains-plugin</artifactId>
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<version>3.0.0</version>
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<executions>
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<execution>
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<goals>
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<goal>toolchain</goal>
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</goals>
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<configuration>
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<toolchains>
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<jdk>
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<version>8</version>
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</jdk>
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</toolchains>
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</configuration>
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</execution>
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</executions>
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</plugin>
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</plugins>
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</build>
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<dependencies>
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<dependency>
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<groupId>org.junit.jupiter</groupId>
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<artifactId>junit-jupiter-api</artifactId>
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<version>5.4.2</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>org.junit.jupiter</groupId>
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<artifactId>junit-jupiter-engine</artifactId>
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<version>5.4.2</version>
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<scope>test</scope>
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</dependency>
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</dependencies>
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</project>
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Add Configuration for Specific JDK Version in Modules
Toolchains configuration in .pom file for JDK8 module:
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<parent>
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<groupId>com.sasa.multipleversions.examples</groupId>
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<artifactId>multiple-java-versions</artifactId>
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<version>1.0.0</version>
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</parent>
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<artifactId>module-jdk-8</artifactId>
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<properties>
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<maven.compiler.source>8</maven.compiler.source>
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<maven.compiler.target>8</maven.compiler.target>
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</properties>
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<build>
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<pluginManagement>
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<plugins>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-surefire-plugin</artifactId>
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<version>3.0.0-M4</version>
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</plugin>
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</plugins>
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</pluginManagement>
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<plugins>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-toolchains-plugin</artifactId>
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<executions>
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<execution>
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<goals>
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<goal>toolchain</goal>
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</goals>
39
<configuration>
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<toolchains>
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<jdk>
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<version>8</version>
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</jdk>
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</toolchains>
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</configuration>
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</execution>
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</executions>
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</plugin>
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</plugins>
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</build>
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52
<dependencies>
53
<dependency>
54
<groupId>javax.validation</groupId>
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<artifactId>validation-api</artifactId>
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<version>2.0.0.Final</version>
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</dependency>
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<dependency>
59
<groupId>junit</groupId>
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<artifactId>junit</artifactId>
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<version>4.4</version>
62
<scope>test</scope>
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</dependency>
64
</dependencies>
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</project>
67
Toolchains configuration in .pom file for JDK11 module:
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1
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<parent>
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<groupId>com.sasa.multipleversions.examples</groupId>
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<artifactId>multiple-java-versions</artifactId>
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<version>1.0.0</version>
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</parent>
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<artifactId>module-jdk-11</artifactId>
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<properties>
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<maven.compiler.source>11</maven.compiler.source>
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<maven.compiler.target>11</maven.compiler.target>
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</properties>
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<build>
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<pluginManagement>
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<plugins>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-surefire-plugin</artifactId>
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<version>3.0.0-M4</version>
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</plugin>
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</plugins>
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</pluginManagement>
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<plugins>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-toolchains-plugin</artifactId>
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<executions>
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<execution>
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<goals>
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<goal>toolchain</goal>
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</goals>
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<configuration>
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<toolchains>
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<jdk>
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<version>11</version>
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</jdk>
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</toolchains>
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</configuration>
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</execution>
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</executions>
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</plugin>
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</plugins>
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</build>
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<dependencies>
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<dependency>
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<groupId>javax.validation</groupId>
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<artifactId>validation-api</artifactId>
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<version>2.0.0.Final</version>
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</dependency>
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<dependency>
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<groupId>junit</groupId>
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<artifactId>junit</artifactId>
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<version>4.4</version>
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<scope>test</scope>
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</dependency>
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</dependencies>
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</project>
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Toolchains configuration in .pom file for JDK14 module:
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<parent>
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<groupId>com.sasa.multipleversions.examples</groupId>
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<artifactId>multiple-java-versions</artifactId>
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<version>1.0.0</version>
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</parent>
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<artifactId>module-jdk-14</artifactId>
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<properties>
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<maven.compiler.source>14</maven.compiler.source>
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<maven.compiler.target>14</maven.compiler.target>
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</properties>
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<build>
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<pluginManagement>
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<plugins>
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<plugin>
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<artifactId>maven-compiler-plugin</artifactId>
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<configuration>
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<release>14</release>
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<compilerArgs>
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--enable-preview
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</compilerArgs>
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</configuration>
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</plugin>
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<plugin>
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<artifactId>maven-surefire-plugin</artifactId>
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<configuration>
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<argLine>--enable-preview</argLine>
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</configuration>
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</plugin>
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<plugin>
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<artifactId>maven-failsafe-plugin</artifactId>
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<configuration>
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<argLine>--enable-preview</argLine>
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</configuration>
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</plugin>
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</plugins>
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</pluginManagement>
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<plugins>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-toolchains-plugin</artifactId>
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<executions>
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<execution>
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<goals>
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<goal>toolchain</goal>
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</goals>
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<configuration>
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<toolchains>
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<jdk>
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<version>14</version>
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</jdk>
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</toolchains>
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</configuration>
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</execution>
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</executions>
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</plugin>
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</plugins>
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</build>
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<dependencies>
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<dependency>
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<groupId>javax.validation</groupId>
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<artifactId>validation-api</artifactId>
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<version>2.0.0.Final</version>
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</dependency>
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<dependency>
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<groupId>junit</groupId>
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<artifactId>junit</artifactId>
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<version>4.4</version>
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<scope>test</scope>
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</dependency>
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</dependencies>
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</project>
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-
In the first module, use the feature from JDK 8 and simple JUnit test.
Simple JDK8 feature:
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package com.multipleversion;
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import javax.validation.Valid;
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import java.util.function.IntFunction;
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public class TestJdk8 {
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public TestJdk8() {
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IntFunction<Integer> doubleIt1 = ( final int x) -> x * 2; // Compiles since Java 8
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// IntFunction<Integer> doubleIt2 = (@Valid final var x) -> x * 2; // Will compile from Java 11
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System.out.println("TestJdk8: " + doubleIt1.apply(5));
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}
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}
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Simple test without any assert:
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package com.multipleversion;
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import org.junit.jupiter.api.AfterEach;
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import org.junit.jupiter.api.BeforeAll;
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import org.junit.jupiter.api.Test;
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public class Test8 {
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public static void init() {
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System.out.println("");
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System.out.println("");
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System.out.println("#######################################################################################");
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System.out.println("");
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}
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public void finalize() {
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System.out.println("");
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System.out.println("#######################################################################################");
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System.out.println("");
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System.out.println("");
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}
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public void testJdk8() {
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System.out.println("Test JDK 8");
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System.out.println("");
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TestJdk8 testJdk8 = new TestJdk8();
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}
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}
Second module, use the feature from JDK 11 and simple JUnit test.
Simple JDK11 feature:
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package com.multipleversion;
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import javax.validation.Valid;
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import java.util.function.IntFunction;
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public class TestJdk11 {
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public TestJdk11() {
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// IntFunction<Integer> doubleIt1 = (@Valid final int x) -> x * 2; // Compiles since Java 8
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// We are using 'var' instead of 'int'
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IntFunction<Integer> doubleIt2 = ( final var x) -> x * 2; // Will compile from Java 11
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System.out.println("TestJdk11: " + doubleIt2.apply(5));
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}
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}
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Simple test without any assert:
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package com.multipleversion;
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import org.junit.BeforeClass;
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import org.junit.jupiter.api.AfterEach;
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import org.junit.jupiter.api.BeforeAll;
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import org.junit.jupiter.api.Test;
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public class Test11 {
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10
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public static void init() {
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System.out.println("");
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System.out.println("");
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System.out.println("#######################################################################################");
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System.out.println("");
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}
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public void finalize() {
20
System.out.println("");
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System.out.println("#######################################################################################");
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System.out.println("");
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System.out.println("");
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}
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public void testJdk11() {
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System.out.println("Test JDK 11");
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System.out.println("");
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TestJdk11 testJdk11 = new TestJdk11();
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}
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}
Third module, use the feature from JDK 14 and simple JUnit test
Simple JDK14 feature:
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package com.multipleversion;
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public class TestJdk14 {
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public TestJdk14(Object obj) {
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if (obj instanceof String s) { // instanceof, cast and bind variable in one line.
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if ("jdk14".equalsIgnoreCase(s)) {
8
System.out.println("Equals");
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} else {
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System.out.println("Not Equals");
11
}
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} else {
13
System.out.println("Not a string");
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}
15
}
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}
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Simple test without any assert:
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1
package com.multipleversion;
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import org.junit.jupiter.api.AfterEach;
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import org.junit.jupiter.api.BeforeAll;
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import org.junit.jupiter.api.Test;
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7
public class Test14 {
8
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public static void init() {
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System.out.println("");
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System.out.println("");
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System.out.println("#######################################################################################");
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System.out.println("");
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}
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public void finalize() {
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System.out.println("");
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System.out.println("#######################################################################################");
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System.out.println("");
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System.out.println("");
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}
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public void testJdk14() {
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System.out.println("Test JDK 14");
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System.out.println("");
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TestJdk14 testJdk = new TestJdk14("jdk14");
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TestJdk14 testJdk2 = new TestJdk14("jdk16");
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TestJdk14 testJdk3 = new TestJdk14(1);
35
}
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}
Execute 'mvn clean install' and check logs.
After successful execution you will get logs like:
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1
...
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[INFO] Reactor Summary:
3
[INFO]
4
[INFO] multiple-java-versions ............................. SUCCESS [ 0.673 s]
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[INFO] module-jdk-8 ....................................... SUCCESS [ 3.710 s]
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[INFO] module-jdk-11 ...................................... SUCCESS [ 2.918 s]
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[INFO] module-jdk-14 ...................................... SUCCESS [ 2.762 s]
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[INFO] ------------------------------------------------------------------------
9
[INFO] BUILD SUCCESS
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[INFO] ------------------------------------------------------------------------
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[INFO] Total time: 10.262 s
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[INFO] Finished at: 2020-04-04T14:57:36+02:00
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[INFO] Final Memory: 13M/237M
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[INFO] ------------------------------------------------------------------------
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First module is working with JDK8 and this is visible in logs of successful build:
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1
...
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[INFO] ------------------------------------------------------------------------
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[INFO] Building module-jdk-8 1.0.0
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[INFO] ------------------------------------------------------------------------
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[INFO]
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[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ module-jdk-8 ---
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[INFO]
8
[INFO] --- maven-toolchains-plugin:3.0.0:toolchain (default) @ module-jdk-8 ---
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[INFO] Required toolchain: jdk [ version='8' ]
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[INFO] Found matching toolchain for type jdk: JDK[/usr/lib/jvm/java-8-openjdk-amd64/jre]
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[INFO]
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[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ module-jdk-8 ---
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[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
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[INFO] skip non existing resourceDirectory /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-8/src/main/resources
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[INFO]
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[INFO] --- maven-compiler-plugin:3.8.1:compile (default-compile) @ module-jdk-8 ---
17
[INFO] Toolchain in maven-compiler-plugin: JDK[/usr/lib/jvm/java-8-openjdk-amd64/jre]
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[INFO] Changes detected - recompiling the module!
19
[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
20
[INFO] Compiling 1 source file to /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-8/target/classes
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[INFO]
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[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ module-jdk-8 ---
23
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
24
[INFO] skip non existing resourceDirectory /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-8/src/test/resources
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[INFO]
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[INFO] --- maven-compiler-plugin:3.8.1:testCompile (default-testCompile) @ module-jdk-8 ---
27
[INFO] Toolchain in maven-compiler-plugin: JDK[/usr/lib/jvm/java-8-openjdk-amd64/jre]
28
[INFO] Changes detected - recompiling the module!
29
[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
30
[INFO] Compiling 1 source file to /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-8/target/test-classes
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[INFO]
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[INFO] --- maven-surefire-plugin:3.0.0-M4:test (default-test) @ module-jdk-8 ---
33
[INFO] Toolchain in maven-surefire-plugin: JDK[/usr/lib/jvm/java-8-openjdk-amd64/jre]
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[INFO]
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[INFO] -------------------------------------------------------
36
[INFO] T E S T S
37
[INFO] -------------------------------------------------------
38
[INFO] Running com.multipleversion.Test8
39
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41
#######################################################################################
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43
Test JDK 8
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45
TestJdk8: 10
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#######################################################################################
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[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.034 s - in com.multipleversion.Test8
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[INFO]
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[INFO] Results:
53
[INFO]
54
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
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[INFO]
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[INFO]
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[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ module-jdk-8 ---
58
[INFO] Building jar: /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-8/target/module-jdk-8-1.0.0.jar
59
[INFO]
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[INFO] --- maven-install-plugin:2.5.2:install (default-install) @ module-jdk-8 ---
61
[INFO] Installing /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-8/target/module-jdk-8-1.0.0.jar to /home/sasa/.m2/repository/com/sasa/multipleversions/examples/module-jdk-8/1.0.0/module-jdk-8-1.0.0.jar
62
[INFO] Installing /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-8/pom.xml to /home/sasa/.m2/repository/com/sasa/multipleversions/examples/module-jdk-8/1.0.0/module-jdk-8-1.0.0.pom
63
[INFO]
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...
From logs is visible that module-jdk-8 is using maven-toolchains-plugin and set JDK version 8:
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[INFO] --- maven-toolchains-plugin:3.0.0:toolchain (default) @ module-jdk-8 ---
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[INFO] Required toolchain: jdk [ version='8' ]
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[INFO] Found matching toolchain for type jdk: JDK[/usr/lib/jvm/java-8-openjdk-amd64/jre]
The second module is working with JDK11 and this is visible in logs of successful build:
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...
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[INFO]
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[INFO] ------------------------------------------------------------------------
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[INFO] Building module-jdk-11 1.0.0
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[INFO] ------------------------------------------------------------------------
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[INFO]
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[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ module-jdk-11 ---
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[INFO]
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[INFO] --- maven-toolchains-plugin:3.0.0:toolchain (default) @ module-jdk-11 ---
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[INFO] Required toolchain: jdk [ version='11' ]
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[INFO] Found matching toolchain for type jdk: JDK[/home/sasa/Downloads/jdk11/amazon-corretto-11.0.6.10.1-linux-x64]
12
[INFO]
13
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ module-jdk-11 ---
14
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
15
[INFO] skip non existing resourceDirectory /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-11/src/main/resources
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[INFO]
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[INFO] --- maven-compiler-plugin:3.8.1:compile (default-compile) @ module-jdk-11 ---
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[INFO] Toolchain in maven-compiler-plugin: JDK[/home/sasa/Downloads/jdk11/amazon-corretto-11.0.6.10.1-linux-x64]
19
[INFO] Changes detected - recompiling the module!
20
[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
21
[INFO] Compiling 1 source file to /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-11/target/classes
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[INFO]
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[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ module-jdk-11 ---
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[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
25
[INFO] skip non existing resourceDirectory /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-11/src/test/resources
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[INFO]
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[INFO] --- maven-compiler-plugin:3.8.1:testCompile (default-testCompile) @ module-jdk-11 ---
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[INFO] Toolchain in maven-compiler-plugin: JDK[/home/sasa/Downloads/jdk11/amazon-corretto-11.0.6.10.1-linux-x64]
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[INFO] Changes detected - recompiling the module!
30
[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
31
[INFO] Compiling 1 source file to /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-11/target/test-classes
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[INFO]
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[INFO] --- maven-surefire-plugin:3.0.0-M4:test (default-test) @ module-jdk-11 ---
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[INFO] Toolchain in maven-surefire-plugin: JDK[/home/sasa/Downloads/jdk11/amazon-corretto-11.0.6.10.1-linux-x64]
35
[INFO]
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[INFO] -------------------------------------------------------
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[INFO] T E S T S
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[INFO] -------------------------------------------------------
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[INFO] Running com.multipleversion.Test11
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#######################################################################################
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Test JDK 11
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TestJdk11: 10
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#######################################################################################
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[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.06 s - in com.multipleversion.Test11
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[INFO]
53
[INFO] Results:
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[INFO]
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[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
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[INFO]
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[INFO]
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[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ module-jdk-11 ---
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[INFO] Building jar: /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-11/target/module-jdk-11-1.0.0.jar
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[INFO]
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[INFO] --- maven-install-plugin:2.5.2:install (default-install) @ module-jdk-11 ---
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[INFO] Installing /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-11/target/module-jdk-11-1.0.0.jar to /home/sasa/.m2/repository/com/sasa/multipleversions/examples/module-jdk-11/1.0.0/module-jdk-11-1.0.0.jar
63
[INFO] Installing /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-11/pom.xml to /home/sasa/.m2/repository/com/sasa/multipleversions/examples/module-jdk-11/1.0.0/module-jdk-11-1.0.0.pom
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[INFO]
65
...
From logs is visible that module-jdk-11 is using maven-toolchains-plugin and set JDK version 11:
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[INFO] --- maven-toolchains-plugin:3.0.0:toolchain (default) @ module-jdk-11 ---
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[INFO] Required toolchain: jdk [ version='11' ]
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[INFO] Found matching toolchain for type jdk: JDK[/home/sasa/Downloads/jdk11/amazon-corretto-11.0.6.10.1-linux-x64]
The third module is working with JDK14 and this is visible in logs of successful build:
Java
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65
1
...
2
[INFO]
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[INFO] ------------------------------------------------------------------------
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[INFO] Building module-jdk-14 1.0.0
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[INFO] ------------------------------------------------------------------------
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[INFO]
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[INFO] --- maven-clean-plugin:2.5:clean (default-clean) module-jdk-14 ---
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[INFO]
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[INFO] --- maven-toolchains-plugin:3.0.0:toolchain (default) module-jdk-14 ---
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[INFO] Required toolchain: jdk [ version='14' ]
11
[INFO] Found matching toolchain for type jdk: JDK[/home/sasa/Downloads/jdk11/jdk-14]
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[INFO]
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[INFO] --- maven-resources-plugin:2.6:resources (default-resources) module-jdk-14 ---
14
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
15
[INFO] skip non existing resourceDirectory /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-14/src/main/resources
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[INFO]
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[INFO] --- maven-compiler-plugin:3.8.1:compile (default-compile) module-jdk-14 ---
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[INFO] Toolchain in maven-compiler-plugin: JDK[/home/sasa/Downloads/jdk11/jdk-14]
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[INFO] Changes detected - recompiling the module!
20
[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
21
[INFO] Compiling 1 source file to /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-14/target/classes
22
[INFO]
23
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) module-jdk-14 ---
24
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
25
[INFO] skip non existing resourceDirectory /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-14/src/test/resources
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[INFO]
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[INFO] --- maven-compiler-plugin:3.8.1:testCompile (default-testCompile) module-jdk-14 ---
28
[INFO] Toolchain in maven-compiler-plugin: JDK[/home/sasa/Downloads/jdk11/jdk-14]
29
[INFO] Changes detected - recompiling the module!
30
[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
31
[INFO] Compiling 1 source file to /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-14/target/test-classes
32
[INFO]
33
[INFO] --- maven-surefire-plugin:3.0.0-M4:test (default-test) module-jdk-14 ---
34
[INFO] Toolchain in maven-surefire-plugin: JDK[/home/sasa/Downloads/jdk11/jdk-14]
35
[INFO]
36
[INFO] -------------------------------------------------------
37
[INFO] T E S T S
38
[INFO] -------------------------------------------------------
39
[INFO] Running com.multipleversion.Test14
40
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#######################################################################################
43
44
Test JDK 14
45
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Equals
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Not Equals
48
Not a string
49
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#######################################################################################
51
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[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.049 s - in com.multipleversion.Test14
54
[INFO]
55
[INFO] Results:
56
[INFO]
57
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
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[INFO]
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[INFO]
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[INFO] --- maven-jar-plugin:2.4:jar (default-jar) module-jdk-14 ---
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[INFO] Building jar: /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-14/target/module-jdk-14-1.0.0.jar
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[INFO]
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[INFO] --- maven-install-plugin:2.5.2:install (default-install) module-jdk-14 ---
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[INFO] Installing /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-14/target/module-jdk-14-1.0.0.jar to /home/sasa/.m2/repository/com/sasa/multipleversions/examples/module-jdk-14/1.0.0/module-jdk-14-1.0.0.jar
65
[INFO] Installing /home/sasa/Sasa Podaci/Podaci/Develpoment/dzone-article/test/multiple-java-versions/module-jdk-14/pom.xml to /home/sasa/.m2/repository/com/sasa/multipleversions/examples/module-jdk-14/1.0.0/module-jdk-14-1.0.0.pom
66
...
From logs is visible that module-jdk-14 is using maven-toolchains-plugin and set JDK version 14:
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[INFO] --- maven-toolchains-plugin:3.0.0:toolchain (default) module-jdk-14 ---
2
[INFO] Required toolchain: jdk [ version='14' ]
3
[INFO] Found matching toolchain for type jdk: JDK[/home/sasa/Downloads/jdk11/jdk-14]
Check Java 14 Features in IntelliJ
IntelliJ will release a new version in April 2020 with support for Java 14 features. You can check those new features and how they are supported in IntelliJ:
https://blog.jetbrains.com/
Source Code for This Example
Source code for this example, can be found on GitHub: https://github.com/sasastarcevic/multiple-java-versions?files=1
I hope that this practical example will help you to speed up your migration process. Wishing you all the best; stay healthy, and have a nice day.
Java (programming language)
Apache Maven
Opinions expressed by DZone contributors are their own.
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