How to enable Logger.debug() in Log4j

Question

While trying to execute the following lines only the last two statements are displayed(\"Here is some ERROR\" and \"Here is some FATAL\") and the first three statements are

Answer 1

Here's a quick one-line hack that I occasionally use to temporarily turn on log4j debug logging in a JUnit test:

Logger.getRootLogger().setLevel(Level.DEBUG);

or if you want to avoid adding imports:

org.apache.log4j.Logger.getRootLogger().setLevel(
      org.apache.log4j.Level.DEBUG);

Note: this hack doesn't work in log4j2 because setLevel has been removed from the API, and there doesn't appear to be equivalent functionality.