In pom.xml, defined this maven.compiler.source properties to tell Maven to use Java 8 to compile the project.

1. Maven Properties

Java 8

pom.xml

    <properties>
        <maven.compiler.target>1.8</maven.compiler.target>
        <maven.compiler.source>1.8</maven.compiler.source>
    </properties>

Java 7

pom.xml

    <properties>
        <maven.compiler.target>1.7</maven.compiler.target>
        <maven.compiler.source>1.7</maven.compiler.source>
    </properties>

2. Compiler Plugin

Alternative, configure the plugin directly.

pom.xml

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.6.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

References

  1. Maven – Setting the -source and -target of the Java Compiler
  2. How to compile Maven project with different JDK version?