The Log class:
API for sending log output.
Generally, use the
Log.v()Log.d()Log.i()Log.w()andLog.e()methods.The order in terms of verbosity, from least to most is
ERROR,WARN,INFO,DEBUG,VERBOSE. Verbose should never be compiled into an application except during development. Debug logs are compiled in but stripped at runtime. Error, warning and info logs are always kept.
Outside of Android, System.out.println(String msg) is used.
Oracle
docs.oracle.com › javase › 8 › docs › technotes › guides › deploy › console_trace_log.html
22 Java Console, Tracing, and Logging
April 21, 2026 - This topic describes the Java Console, a debugging aid that redirects any System.out and System.err to the console window. The console is available for applets running with Java Plug-in and applications running with Java Web Start.
Delft Stack
delftstack.com › home › howto › java › console log in java
console.log in Java | Delft Stack
March 4, 2025 - This article introduces console.log in Java, exploring various methods for logging messages to the console. Learn how to use System.out.println, Log4j, and SLF4J for effective debugging and logging practices in your Java applications. Discover the best practices and enhance your development ...
android - What's the console.log() of java? - Stack Overflow
I'm working on building an Android app and I'm wondering what the best approach is to debugging like that of console.log in javascript More on stackoverflow.com
Using java.util.logging to log on the console - Stack Overflow
the logger is used inside the class, may also be configurated by the class. the handler may be set globally. so you might have different handlers, for output to console and/or file. you definetly have different loggers, e.g. for each class. More on stackoverflow.com
Console.log in Java extension? - Jazz Forum
Greetings, When "developing" javascripts within RTC, I find the console.log method to be very handy. What is the best "printf" method of debugging I can use from within an extension? I have a working Operation Advisor, but am now adding functionality to it and a piece is... More on jazz.net
Showcase Thread
aiofastnet - optimized (up to x2.2 faster) drop-in replacements for asyncio networking APIs As a part of algorithmic trading project I had to look into the actual performance of uvloop and asyncio network API. Turned out it wasn't so great, TLS part is especially bad, also in uvloop. Lot's of plumbing code and memory copying. I tried to push PRs to uvloop but the project is almost unmaintained these days. Took more than 1 year to get some of the relatively small PRs reviewed and merged, I'm not even talking about big changes. Eventually I came up with a much cleaner and loop agnostic way to improve networking API performance. https://github.com/tarasko/aiofastnet What My Project Does Provides drop-in optimized versions of asyncio networking APIs: loop.create_connection() loop.open_connection() loop.create_server() loop.start_server() loop.start_tls() loop.sendfile() Target Audience This project is mainly for developers who already use asyncio transports/protocols and want better performance without redesigning their code. It is probably most relevant for people building: ASGI/HTTP/Websocket or RPC clients and servers proxies database clients/servers custom binary protocols other protocol-heavy network services Comparison Compared to uvloop/winloop, aiofastnet is not a separate event loop. It focuses specifically on the transport/TLS layer and works with the loop you already use. Feedback is very welcome! More on reddit.com
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April 4, 2026Videos
Java Console Output - Java Tutorial | #4 - YouTube
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Logging Inside of Java - YouTube
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Java 101 - Print to Console, Variables, Data Types (38 Minutes) ...
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Save console output to a file with Date and Time in Java | Selenium ...
DigitalOcean
digitalocean.com › community › tutorials › logger-in-java-logging-example
Java Logger: Logging Examples with Log4j & SLF4J | DigitalOcean
August 3, 2022 - Implement logging in Java with Logger, Log4j, and SLF4J. Complete guide covering configuration, log levels, best practices, and real-world examples.
Top answer 1 of 4
141
The Log class:
API for sending log output.
Generally, use the
Log.v()Log.d()Log.i()Log.w()andLog.e()methods.The order in terms of verbosity, from least to most is
ERROR,WARN,INFO,DEBUG,VERBOSE. Verbose should never be compiled into an application except during development. Debug logs are compiled in but stripped at runtime. Error, warning and info logs are always kept.
Outside of Android, System.out.println(String msg) is used.
2 of 4
25
Use the Android logging utility.
http://developer.android.com/reference/android/util/Log.html
Log has a bunch of static methods for accessing the different log levels. The common thread is that they always accept at least a tag and a log message.
Tags are a way of filtering output in your log messages. You can use them to wade through the thousands of log messages you'll see and find the ones you're specifically looking for.
You use the Log functions in Android by accessing the Log.x objects (where the x method is the log level). For example:
CopyLog.d("MyTagGoesHere", "This is my log message at the debug level here");
Log.e("MyTagGoesHere", "This is my log message at the error level here");
I usually make it a point to make the tag my class name so I know where the log message was generated too. Saves a lot of time later on in the game.
You can see your log messages using the logcat tool for android:
Copyadb logcat
Or by opening the eclipse Logcat view by going to the menu bar
CopyWindow->Show View->Other then select the Android menu and the LogCat view
Sentry
blog.sentry.io › a-guide-to-logging-and-debugging-in-java
Logging & Debugging in Java - Guide | Sentry Blog
September 25, 2025 - Unsaved console logs disappear when the program stops, making it difficult to keep a history of what happened. They also don’t allow you to categorize messages by severity, which makes it hard to spot critical issues in the output. Basic logging in Java can be achieved using the built-in java.util.logging package.
Loggly
loggly.com › home › java logging basics
Java Logging Basics - The Ultimate Guide To Logging - Loggly
June 27, 2025 - The Appender then formats the record ... as the console, a file, or another application. Additionally, you can use one or more Filters to specify which Appenders should be used for which events. Filters aren't required, but they give you greater control over the flow of your log messages. Source: https://docs.oracle.com/javase/7/docs/te...
SigNoz
signoz.io › guides › java logging: from println to production-ready logs
Java Logging: Setup, Log4j2, SLF4J & Monitoring | SigNoz
July 10, 2024 - Learn Java logging with Log4j2, SLF4J, log levels, MDC, JSON logs, async logging, troubleshooting, and monitoring with SigNoz.
Baeldung
baeldung.com › home › logging › log4j2 – logging to both file and console
Log4j2 – Logging to Both File and Console | Baeldung
January 8, 2024 - In this tutorial, we’ll explore how to log messages to both file and console using the Apache Log4j2 library. This is very useful in a non-prod environment where we may want to see debug messages in the console, and we may want to persist the higher level logs to a file for later analysis. Let’s start by creating a Java ...
Vogella
vogella.com › tutorials › Logging › article.html
Java Logging API - Tutorial
Log levels INFO and higher will be automatically written to the console. Each handler’s output can be configured with a formatter ... You can also build your own formatter. The following is an example of a formatter which will create HTML output. package com.vogella.logger; import java.text.SimpleDateFormat; import java.util.Date; import java.util.logging.Formatter; import java.util.logging.Handler; import java.util.logging.Level; import java.util.logging.LogRecord; // this custom formatter formats parts of a log record to a single line class MyHtmlFormatter extends Formatter { // this metho
LabEx
labex.io › tutorials › java-how-to-print-output-to-console-in-java-417652
How to print output to console in Java | LabEx
Learn how to print basic and advanced console output in Java programming. Discover techniques to display text, variables, and formatted data in the console.
CrowdStrike
crowdstrike.com › en-us › guides › java-logging
Java Logging Guide: The Basics
September 19, 2024 - In this overview, we introduce the basic logging concepts for Java applications as well as available logging frameworks and their supported configurations.
IBM
ibm.com › support › pages › enable-java-console-logging
Enable Java Console logging
After log in, if you do not have the right authorization for this document, there will be instructions on what to do next.
javaspring
javaspring.net › blog › console-log-java
Mastering Console Logging in Java — javaspring.net
This blog post will delve into the fundamental concepts of console logging in Java, explore various usage methods, discuss common practices, and present best practices to help you use console logging effectively.
Top answer 1 of 3
33
Very simple, a logger can have several handlers, with each a different level.
handler.setLevel(Level.ALL);
2 of 3
13
Logging on the standard System.out stream could be easily done by adding a StreamHandler handler:
logger.addHandler(new StreamHandler(System.out, new SimpleFormatter()))
Hitachi
itpfdoc.hitachi.co.jp › manuals › 3021 › 3021336100e › H3610046.HTM
3.5.2 Collecting a Java console log : Job Management Partner 1/Data Highway - Server User's Guide
Click the Advanced tab, and then select all the check boxes under Debugging. Click the OK button. Restart Internet Explorer (IE). Do the same operation as when the problem occurred. In the task tray, right-click the displayed Java icon. Click Open version Console...
Better Stack
betterstack.com › community › guides › logging › how-to-start-logging-with-java
10 Best Practices for Logging in Java | Better Stack Community
January 22, 2026 - In this tutorial, we covered some best practice guidelines that you should follow to help you create a comprehensive and effective logging system for your Java application.
Codecademy
codecademy.com › docs › java › output › .println()
Java | Output | .println() | Codecademy
November 5, 2022 - Prints its argument to the console followed by a new line.
Jazz Community Site
jazz.net › forum › questions › 137262 › consolelog-in-java-extension
Console.log in Java extension? - Jazz Forum
January 2, 2014 - I just start my normal server in debug mode. then connect from Eclipse to a Remote app. debug both client and server at the same time. only case where I can't do this is when I develop a jazz client side plugin, ten I need to start another eclipse locally in debug mode. just add one line to the server.startup.bat as the last JAVA_OPTS line set JAVA_OPTS=%JAVA_OPTS% -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=3388 then the remote app port is 3388 · Register or log in to post your answer.
GeeksforGeeks
geeksforgeeks.org › java › logger-log-method-in-java-with-examples
Logger log() Method in Java with Examples - GeeksforGeeks
July 12, 2025 - Return value: This method returns nothing Program 4: Method log(Level level, String msg, Throwable thrown) ... // Java program to demonstrate // Logger.log(Level level, String msg, Throwable thrown) import java.util.logging.Level; import java.util.logging.Logger; public class GFG { public static void main(String[] args) { // Create a Logger Logger logger = Logger.getLogger( GFG.class.getName()); // log messages using // log(Level level, String msg, Throwable thrown) logger.log(Level.SEVERE, "logging:", new RuntimeException("Error")); logger.log(Level.WARNING, "logging: ", new Exception("Exception")); } } Output:
Oracle
java.com › en › download › help › javaconsole.html
How do I enable and view the Java Console?
The Java Console provides information about the Java version, user home directory, and any error message that occurs while running an applet or application.