How to set SLF4J in IntelliJ with Gradle

Question

I'm having a hard time configuring SLF4J with Gradle in IntelliJ. No matter what I do I get this message:

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder". SLF4J: Defaulting to no-operation (NOP) logger implementation SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.

I'm trying to log in to the console and after testing to a file in a specific folder. Any help would be great.

build.gradle file:

plugins {
    id 'java'
    id 'org.openjfx.javafxplugin' version '0.0.8'
    id 'application'
}

version '1.0-SNAPSHOT'

sourceCompatibility = 1.8

repositories {
    mavenCentral()
    jcenter()
    google()
}

dependencies {
    compile group: 'com.googlecode.json-simple', name: 'json-simple', version: '1.+'
    testCompile group: 'junit', name: 'junit', version: '4.12'
    compile group: 'org.apache.poi', name: 'poi', version: '4.+'
    compile group: 'org.apache.poi', name: 'poi-ooxml', version: '4.+'
    compile group: 'org.slf4j', name: 'slf4j-api', version: '1.7.+'
    // compile group: 'ch.qos.logback', name: 'logback-classic', version: '1.+'
    implementation 'com.google.firebase:firebase-admin:6.11.0'
}
javafx {
    version = '12'
    modules = ['javafx.controls', 'javafx.fxml']
}

mainClassName = 'ui.Main'
apply plugin: 'org.openjfx.javafxplugin'

apply plugin: 'idea'

jar {
    manifest {
        attributes 'Main-Class': mainClassName
    }
    from {
        configurations.runtimeClasspath.collect { it.isDirectory() ? it : zipTree(it) }
    }
}

log4j.properties file (in src/main/resources/):

# Define the root logger with appender file
log4j.rootLogger = DEBUG, FILE

# Define the file appender
log4j.appender.FILE=org.apache.log4j.FileAppender
log4j.appender.FILE.File=${log}/log.out

# Define the layout for file appender
log4j.appender.FILE.layout=org.apache.log4j.PatternLayout
log4j.appender.FILE.layout.conversionPattern=%m%n

Answer 1

You need a logging framework on your classpath. SLF4J is a logging facade that supports multiple implementations (logback, log4j etc.). However, if you don't include a specific backend, SLF4J defaults to a NOP implementation that simply ignores everything. :)

If you want to use log4j, you need to include a binding for it like this:

compile group: 'org.slf4j', name: 'slf4j-log4j12', version: '1.7.29'

For more information, see http://www.slf4j.org/manual.html#swapping