packaged JAR's main class throwing error when using Google Guava

Question

I created a new project to set Google Guava.

This is my POM.xml.

<dependencies>
    <!-- https://mvnrepository.com/artifact/com.google.guava/guava -->
    <dependency>
        <groupId>com.google.guava</groupId>
        <artifactId>guava</artifactId>
        <version>20.0</version>
    </dependency>
</dependencies>
<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-jar-plugin</artifactId>
            <configuration>
                <archive>
                    <manifest>
                        <mainClass>InetAddressTest</mainClass>
                    </manifest>
                </archive>
            </configuration>
        </plugin>
    </plugins>
</build>

This is my main method.

public static void main(String[] args) throws Exception {
    try {
        System.out.println(InetAddresses.isInetAddress("127.0.0.1"));
    } catch (NoClassDefFoundError exp) {
        System.out.println(exp);
    }
}

I am able to run it inside my IDE.

I can package it with mvn package

When I run it java -jar target/<NAME>.jar, it throws an exception java.lang.NoClassDefFoundError: com/google/common/net/InetAddresses

I tried to browse the solutions. But they haven't worked so far.

I am guessing (based on other problems) that I am missing some dependencies for Guava?

When you package the jar, you will need to package the dependencies as well as part of it. — OTM, Jul 17 '17 at 18:05
Please also see. https://stackoverflow.com/questions/574594/how-can-i-create-an-executable-jar-with-dependencies-using-maven — OTM, Jul 17 '17 at 18:14

Rishikesh Darandale · Answer 1 · 2017-07-18T06:12:03.023

1

Looks like google guava itself is not in the class path, try setting the class path as below to your java command:

java -jar -classpath .:./{path_to_gauva_jar} target/<name>.Jar

Change the separator as per your operating system.

edited Jul 18 '17 at 06:12

answered Jul 17 '17 at 18:09

Rishikesh Darandale

3,222
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score 1 · Accepted Answer · answered Jul 17 '17 at 18:14

You have two options :-

1) While executing the Java command use the -cp or -classpath option to list all the required jar files.

2) Include all the dependencies in your jar by using the maven shade plugin in your pom.xml

<plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>2.4.2</version>
                <configuration>
                    <finalName>uber-${project.artifactId}-${project.version}</finalName>
                </configuration>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>

packaged JAR's main class throwing error when using Google Guava

2 Answers2