Maven and Class not found exception while running .jar file

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I started learning maven with simple hello world app and added some dependencies:

    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-simple</artifactId>
        <version>${slf4j.version}</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>${slf4j.version}</version>
    </dependency>

And changed System.out.println("Hello World") to:

    var logger = LoggerFactory.getLogger(App.class);
    logger.info("Hello World");

Then I created .jar file using maven lifecycle and when I try to run it I get this error:

    Exception in thread "main" java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory
    at io.github.mat3e.App.main(App.java:11)
    Caused by: java.lang.ClassNotFoundException: org.slf4j.LoggerFactory
    at           java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:602)
    at   java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
    ... 1 more

Why is that?

maven exception java
1 Answers

Recommended way to use SLF4J logger API by adding following dependency :

        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.3</version>
        </dependency>

In your java class fetch the logger instance as follows :

 private static final Logger logger = LoggerFactory.getLogger(App.class); 
 logger.info("Hello World");

Should work fine.

check out the documentation

user_85555410
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