Skip to main content

Use logger instead of System.out print statements

org.openrewrite.java.logging.SystemOutToLogging

Replace System.out print statements with a logger.

Recipe source​

GitHub, Issue Tracker, Maven Central

This recipe is available under the Moderne Source Available License.

Options​

TypeNameDescriptionExample
BooleanaddLoggerOptional. Add a logger field to the class if it isn't already present.
StringloggerNameOptional. The name of the logger to use when generating a field.log
StringloggingFrameworkOptional. The logging framework to use. Valid options: SLF4J, Log4J1, Log4J2, JUL, COMMONS
StringlevelOptional. The logging level to turn System.out print statements into. Valid options: trace, debug, info

Example​

Parameters​
ParameterValue
addLoggernull
loggerNameLOGGER
loggingFrameworknull
leveldebug
Before​
import org.slf4j.Logger;
class Test {
    int n;
    Logger logger;

    void test() {
        System.out.println("Oh " + n + " no");
    }
}
After​
import org.slf4j.Logger;
class Test {
    int n;
    Logger logger;

    void test() {
        logger.debug("Oh {} no", n);
    }
}

Usage​

This recipe has no required configuration options. It can be activated by adding a dependency on org.openrewrite.recipe:rewrite-logging-frameworks in your build file or by running a shell command (in which case no build changes are needed):

  1. Add the following to your build.gradle file:
build.gradle
plugins {
    id("org.openrewrite.rewrite") version("7.6.1")
}

rewrite {
    activeRecipe("org.openrewrite.java.logging.SystemOutToLogging")
    setExportDatatables(true)
}

repositories {
    mavenCentral()
}

dependencies {
    rewrite("org.openrewrite.recipe:rewrite-logging-frameworks:3.8.0")
}
  1. Run gradle rewriteRun to run the recipe.

See how this recipe works across multiple open-source repositories​

Run this recipe on OSS repos at scale with the Moderne SaaS.

The community edition of the Moderne platform enables you to easily run recipes across thousands of open-source repositories.

Please contact Moderne for more information about safely running the recipes on your own codebase in a private SaaS.

Data Tables​

Source files that had results​

org.openrewrite.table.SourcesFileResults

Source files that were modified by the recipe run.

Column NameDescription
Source path before the runThe source path of the file before the run. null when a source file was created during the run.
Source path after the runA recipe may modify the source path. This is the path after the run. null when a source file was deleted during the run.
Parent of the recipe that made changesIn a hierarchical recipe, the parent of the recipe that made a change. Empty if this is the root of a hierarchy or if the recipe is not hierarchical at all.
Recipe that made changesThe specific recipe that made a change.
Estimated time savingAn estimated effort that a developer to fix manually instead of using this recipe, in unit of seconds.
CycleThe recipe cycle in which the change was made.

Contributors​

Jonathan Schneider, Tim te Beek, Knut Wannheden, Sam Snyder, Michael Keppler, Adriano Machado