How to Do Logging In Java?

8 minutes read

In Java, logging can be done using the built-in java.util.logging package or by using popular logging frameworks such as Log4j, Logback, or SLF4J. To implement logging in Java, you can follow these steps:

  1. Import the necessary logging library or package into your Java program.
  2. Create a logger object using the getLogger() method provided by the logging library.
  3. Use logger methods such as info(), warning(), severe(), etc. to log messages at different severity levels.
  4. Customize the logging format, output destination, and log levels as needed.
  5. Handle exceptions and log error messages to track and troubleshoot issues in your Java application.


Logging is an essential practice in software development to track the behavior of an application, monitor its performance, and debug any issues that may arise. By implementing proper logging in your Java code, you can improve the maintainability and reliability of your application.

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How to use log rotation in Java?

In Java, you can utilize log rotation by using the built-in logging framework, java.util.logging. Here's how you can implement log rotation in your Java application:

  1. First, set up the logging properties in a properties file (for example, logging.properties) to configure the log rotation settings. Here is an example configuration for log rotation:
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handlers=java.util.logging.FileHandler
java.util.logging.FileHandler.pattern = logs/myapp.log
java.util.logging.FileHandler.limit = 1000000
java.util.logging.FileHandler.count = 5
java.util.logging.FileHandler.append = true


In this configuration, the FileHandler pattern specifies the log file name and location, the limit sets the maximum size of the log file in bytes before it rotates, count sets the number of log files to keep and append specifies whether to append to an existing log file or create a new one.

  1. Load the logging properties file in your Java code using LogManager class:
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LogManager.getLogManager().readConfiguration(new FileInputStream("logging.properties"));


  1. Log messages in your Java application using the Logger class:
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Logger logger = Logger.getLogger("myLogger");
logger.info("This is a log message");


  1. To rotate the log file based on the specified settings, you can trigger log rotation programmatically by closing and reopening the log file handler:
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Handler handler = Logger.getLogger("").getHandlers()[0];
if (handler instanceof FileHandler) {
    FileHandler fileHandler = (FileHandler) handler;
    fileHandler.close();
    fileHandler.open();
}


This will force the log file to rotate based on the configured settings.


By following these steps, you can implement log rotation in your Java application using the java.util.logging framework.


How to disable logging in Java?

Logging can be disabled in Java by setting the logging level to OFF for the root logger. This can be done by adding the following code before any logging is performed:

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import java.util.logging.Logger;

public class DisableLogging {
    public static void main(String[] args) {
        Logger rootLogger = Logger.getLogger("");
        rootLogger.setLevel(java.util.logging.Level.OFF);
        
        // Any logging statements here will not be displayed
    }
}


By setting the logging level to OFF, all log messages below this level will be ignored and not displayed. This effectively disables logging for the entire application.


How to set up logging in Java?

To set up logging in Java, you can use the built-in Java logging framework, java.util.logging. Here's how you can set it up:

  1. Import the necessary classes:
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import java.util.logging.Logger;
import java.util.logging.Level;


  1. Create a Logger instance in your class:
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private static final Logger logger = Logger.getLogger(YourClass.class.getName());


  1. Configure the logging level and handler. You can do this in a separate configuration file or programmatically in your code. Here's an example of setting the level to INFO and adding a ConsoleHandler:
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logger.setLevel(Level.INFO);
logger.addHandler(new ConsoleHandler());


  1. Use the logger to log messages at different levels in your code:
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logger.severe("This is a severe message");
logger.warning("This is a warning message");
logger.info("This is an info message");
logger.config("This is a config message");
logger.fine("This is a fine message");
logger.finer("This is a finer message");
logger.finest("This is the finest message");


  1. Run your application and view the logged messages in the console.


By following these steps, you can easily set up logging in Java using java.util.logging. You can also use other logging frameworks such as Log4j or SLF4J for more advanced logging features.

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