Logger finest() method in Java with Examples

Last Updated : 11 Jul, 2025

The finest() method of a Logger class used to Log an FINEST message.This method is used to pass FINEST types logs to all the registered output Handler objects. FINEST message: FINEST provides highly detailed tracing message.
There are two types of finest() method depending upon the number of the parameters passed.

finest(String msg): This method is used to log a FINEST message.If the logger is enabled for logging FINEST level message then the given message is forwarded to all the registered output Handler objects. Syntax:

public void finest(String msg)

Parameters: This method accepts a single parameter String which is the string message. Return value: This method returns nothing. Below programs illustrate finest(String msg) method: Program 1:

Java

// Java program to demonstrate
// Logger.finest(String msg) method

import java.io.IOException;
import java.util.logging.*;

public class GFG {

    public static void main(String[] args)
        throws SecurityException, IOException
    {

        // Create a Logger
        Logger logger
            = Logger.getLogger(
                GFG.class.getName());

        // Create a file handler object
        // and set formatter to simple formatter
        FileHandler handler = new FileHandler("logs.txt");
        handler.setFormatter(new SimpleFormatter());

        // Add file handler as
        // handler of logs
        logger.addHandler(handler);

        // Set Logger level()
        logger.setLevel(Level.FINEST);

        // Call finest method
        logger.finest("Set Geeks=CODING");
    }
}

The output printed on logs.txt file is shown below. Output:

finest(Supplier msgSupplier): This method is used Log a FINEST message, constructed only if the logging level is such that the message will actually be logged. It means If the logger is enabled for the FINEST message level then the message is constructed by invoking the provided supplier function and forwarded to all the registered output Handler objects. Syntax:

public void finest(Supplier msgSupplier)

Parameters: This method accepts a single parameter msgSupplier which is a function, which when called, produces the desired log message. Return value: This method returns nothing. Below programs illustrate finest(Supplier msgSupplier) method: Program 1:

Java

// Java program to demonstrate
// Logger.finest(Supplier<String>) method

import java.io.IOException;
import java.util.function.Supplier;
import java.util.logging.*;

public class GFG {

    public static void main(String[] args)
        throws SecurityException, IOException
    {

        // Create a Logger
        Logger logger
            = Logger.getLogger(
                GFG.class.getName());

        // Create a file handler object
        // and set formatter to simple formatter
        FileHandler handler
            = new FileHandler("logs.txt");
        handler.setFormatter(new SimpleFormatter());

        // Add file handler as
        // handler of logs
        logger.addHandler(handler);

        // Set Logger level()
        logger.setLevel(Level.FINEST);

        // Create a supplier<String> method
        Supplier<String> StrSupplier
            = () -> new String("You are a geek");

        // Call finest(Supplier<String>)
        logger.finest(StrSupplier);
    }
}