# Lanterna

I found the [*Lanterna*](https://github.com/mabe02/lanterna) library recently.  Haven&#39;t had the opportunity to use it yet but it looks like a more up-to-date alternative to the others.

[![enter image description here][1]][1]


  [1]: https://i.stack.imgur.com/hAB5e.png

There is [Charva][1], which links to native code but has an api based on Swing.
The [screenshots][2] show lots of text windows, so that looks useful.


  [1]: http://www.pitman.co.za/projects/charva/
  [2]: http://www.pitman.co.za/projects/charva/Screenshots.html

Haven&#39;t used it myself, but [Java Curses Library][1] sounds like what you want.


  [1]: http://sourceforge.net/projects/javacurses

[Here][1] is a way to call the ncurses lib using JNI.  I tested this and it works.  


  [1]: http://plindenbaum.blogspot.com/2008/01/java-native-interface-jni-notebook.html

As of 2013, the closest I can find is [Blacken][1].

Blacken is not a curses library per-se. It moves away from the terminal, and instead, renders it&#39;s own &quot;console window.&quot; This has the disadvantage of not looking &quot;console-like.&quot; Instead, you get full (arbitrary) colour support, and a curses-like API (in addition to their main API).

You can also set the font to `Mono` for fixed-width characters.


  [1]: https://code.google.com/p/blacken/

A lot of people seem to agree, that the Singleton pattern has a number of drawbacks and some even suggest avoiding the pattern entirely. There&#39;s an [excellent discussion here][1]. Please direct any comments about the Singleton pattern to that question. 

**My question**: Are there other design patterns, that should be avoided or used with great care?

  [1]: https://stackoverflow.com/questions/137975/what-is-so-bad-about-singletons

Design patterns to avoid

In C++, `sizeof(&#39;a&#39;) == sizeof(char) == 1`. This makes intuitive sense, since `&#39;a&#39;` is a character literal, and `sizeof(char) == 1` as defined by the standard.&lt;br&gt;

In C however, `sizeof(&#39;a&#39;) == sizeof(int)`. That is, it appears that C character literals are actually integers. Does anyone know why? I can find plenty of mentions of this C quirk but no explanation for why it exists.

Why are C character literals ints instead of chars?

I would like to write a Java terminal application that does screen manipulation. Are there any good libraries out there that allow you to manipulate the screen like curses in the *nix/C world?

Minimal features I&#39;m looking for are windowing and user input support.

In feature-speak, I&#39;d like to have a region of the terminal where some data is regularly updated while (at the same time) the user can enter commands/text in some other part of the screen.

What&#39;s a good Java, curses-like, library for terminal applications?

I would like to write a Java terminal application that does screen manipulation. Are there any good libraries out there that allow you to manipulate the screen like curses in the *nix/C world?
Minimal features I'm looking for are windowing and user input support.
In feature-speak, I'd like to have a region of the terminal where some data is regularly updated while (at the same time) the user can enter commands/text in some other part of the screen.

Given a set of Java source code files, how can I compile them into one or more JavaScript files that can be used with hand-crafted JavaScript?

[GWT](http://code.google.com/webtoolkit/) is one option, but every example I&#39;ve seen so far is aimed at building fancy websites. The simple use case of just converting Java source to Javascript that can be used together with handcrafted JavaScript [hasn&#39;t been well-documented](http://depth-first.com/articles/2009/01/06/javascript-for-cheminformatics-cross-compiling-java-to-javascript-with-gwt-revisited#comments).

I started a [thread on the GWT mailing list](http://groups.google.com/group/Google-Web-Toolkit/browse_thread/thread/d9ae879cc249d2cb/b4799e0774a14c50) on this subject, but opinions seem to be mixed on whether this is even feasible.

One person gave a very useful tip, which was to check out [GWT-Exporter](http://code.google.com/p/gwt-exporter/). The problem is that neither source code nor documentation is readily available, although there&#39;s [this](http://groups.google.com/group/Google-Web-Toolkit/browse_thread/thread/201528f512c546f3) and [this](http://timepedia.blogspot.com/2008/06/gwt-exporterthe-next-generation.html).

edit: GWT-Exporter source code is [here](http://code.google.com/p/gwt-exporter/source/browse/)

I&#39;ve also seen [Java2Script](http://j2s.sourceforge.net/index.html). But again, I wasn&#39;t able to find examples of how to solve my simple use case.

What&#39;s the best approach to this problem? Is there something better I&#39;m missing?



How to Cross-Compile Java Source Code to JavaScript?

JUnit will only test those methods in my class that are public.  How do I do junit testing on the ones that are not (i.e., private, protected)?  

I can test them by not using junit, but I was wondering what the junit standard method was.

junit &amp; java : testing non-public methods

We work heavily with serialization and having to specify Serializable tag on every object we use is kind of a burden. Especially when it&#39;s a 3rd-party class that we can&#39;t really change.

The question is: since Serializable is an empty interface and Java provides robust serialization once you add  `implements Serializable` - why didn&#39;t they make everything serializable and that&#39;s it?  

What am I missing?

Why Java needs Serializable interface?

It seems rare to read of a Python &quot;virtual machine&quot; while in Java &quot;virtual machine&quot; is used all the time.

Both interpret byte codes; why call one a virtual machine and the other an interpreter?


Java &quot;Virtual Machine&quot; vs. Python &quot;Interpreter&quot; parlance?

Whenever a question pops up on SO about Java synchronization, some people are very eager to point out that `synchronized(this)` should be avoided. Instead, they claim, a lock on a private reference is to be preferred.

Some of the given reasons are:

 - [some *evil code* may steal your lock][1] (very popular this one, also has an &quot;accidentally&quot; variant)
 - [all synchronized methods within the same class use the exact same lock, which reduces throughput][2]
 - [you are (unnecessarily) exposing too much information][3]

Other people, including me, argue that `synchronized(this)` is an idiom that is used a lot (also in Java libraries), is safe and well understood. It should not be avoided because you have a bug and you don&#39;t have a clue of what is going on in your multithreaded program. In other words: if it is applicable, then use it.

I am interested in seeing some real-world examples (no foobar stuff) where avoiding a lock on `this` is preferable when `synchronized(this)` would also do the job.

Therefore: **should you always avoid `synchronized(this)` and replace it with a lock on a private reference?**  

---

Some further info (updated as answers are given):

 - we are talking about instance synchronization
 - both implicit (`synchronized` methods) and explicit form of `synchronized(this)` are considered
 - if you quote Bloch or other authorities on the subject, don&#39;t leave out the parts you don&#39;t like (e.g. Effective Java, item on Thread Safety: *Typically it is the lock on the instance itself, but there are exceptions.)*
 - if you need granularity in your locking other than `synchronized(this)` provides, then `synchronized(this)` is not applicable so that&#39;s not the issue

  [1]: https://stackoverflow.com/questions/416183/in-java-critical-sections-what-should-i-synchronize-on#416198
  [2]: https://stackoverflow.com/questions/309631/what-cases-require-synchronized-method-access-in-java#309677
  [3]: https://stackoverflow.com/questions/439302/allowing-a-method-to-lock-its-parent-object-in-java#439317

Avoid synchronized(this) in Java?

I do not like to retype `fish` every time I start terminal. I want [Fish][1] on by default. How can I set the Fish shell as my default shell on a Mac?

  [1]: https://en.wikipedia.org/wiki/Fish_(Unix_shell)





How can I set my default shell on a Mac, e.g. to Fish?

When piping the output of a Python program, the Python interpreter gets confused about encoding and sets it to None. This means a program like this:

    # -*- coding: utf-8 -*-
    print u&quot;&#229;&#228;&#246;&quot;

will work fine when run normally, but fail with:

&gt; UnicodeEncodeError: &#39;ascii&#39; codec can&#39;t encode character u&#39;\xa0&#39; in position 0: ordinal not in range(128)

when used in a pipe sequence.

What is the best way to make this work when piping? Can I just tell it to use whatever encoding the shell/filesystem/whatever is using? 

The suggestions I have seen thus far is to modify your site.py directly, or hardcoding the defaultencoding using this hack:

    # -*- coding: utf-8 -*-
    import sys
    reload(sys)
    sys.setdefaultencoding(&#39;utf-8&#39;)
    print u&quot;&#229;&#228;&#246;&quot;

Is there a better way to make piping work?


Setting the correct encoding when piping stdout in Python

i&#39;m doing a dir listing in my .ssh home dir which gives me a strange result:  

    ls -lsa .ssh/
    total 0
    ? ?--------- ? ? ? ?            ? . &#183;
    ? ?--------- ? ? ? ?            ? .. &#183;
    ? ?--------- ? ? ? ?            ? authorized_keys &#183;

The weird thing is, that this only happens for one user and only in this specific directory. If I do the ls after a su -l, everything works as expected.  Another strange thing is, that my xterm shows the dir listing in a red blinking font!
Any ideas what&#39;s causing this to happen?

thx!

**Edit:**  
Here is the dir listing as root:

    ls -lsa
    total 52
    4 drw-------  2 sdd sdd 4096 Feb 10 15:57 .
    4 drwx------ 16 sdd sdd 4096 Feb 10 15:57 ..
    4 -rw-------  1 sdd sdd 1628 Feb 10 15:57 authorized_keys

I&#39;m using ext3.

**Edit2:**  
Thx for the answers, but i still get this:  

    chmod -R 600 /home/sdd/.ssh
    ls -lsan _ssh.old/
    total 0
    ? ?--------- ? ? ? ?            ? .
    ? ?--------- ? ? ? ?            ? ..
    ? ?--------- ? ? ? ?            ? authorized_keys

Only Questionmarks in Linux dirlisting

Is there a way in python to programmatically determine the width of the console? I mean the number of characters that fits in one line without wrapping, not the pixel width of the window.

&lt;b&gt;Edit&lt;/b&gt;

Looking for a solution that works on Linux

How to get Linux console window width in Python

What is the best way to move around on a given very long command line in the terminal?

Say I used the arrow key or &lt;kbd&gt;Ctrl&lt;/kbd&gt;-&lt;kbd&gt;R&lt;/kbd&gt; to get this long command line:

    ./cmd --option1 --option2 --option3 --option4 --option5 --option6 --option7 --option8 --option9 --option10 --option11 --option12 --option13 --option14 --option15 --option16 --option17 --option18 --option19 --option20 --option21 --option22 --option23 --option24 --option25 --option26 --option27 --option28 --option29 --option30 --option31 --option32 --option33 --option34 --option35 --option36 --option37 --option38 --option39 --option40 --option41 --option42 --option43 --option44 --option45 --option46 --option47 --option48 --option49 --option50 

Now I need to move (starting from the beginning or the end of the line) the cursor to `--option25` to modify something there. 

What is the fastest way to get there? What I usually do is &lt;kbd&gt;Ctrl&lt;/kbd&gt;-&lt;kbd&gt;A&lt;/kbd&gt; to get to the beginning and then repeatedly &lt;kbd&gt;Alt&lt;/kbd&gt;-&lt;kbd&gt;F&lt;/kbd&gt; to move forward, word by word (or &lt;kbd&gt;Ctrl&lt;/kbd&gt;-&lt;kbd&gt;E&lt;/kbd&gt; to go the end and &lt;kbd&gt;Alt&lt;/kbd&gt;-&lt;kbd&gt;B&lt;/kbd&gt; to then go backward). But on a long line that takes too much time. There must be a way to search and jump directly to the part I need to modify, e.g. `option25`?


Fastest way(s) to move the cursor on a terminal command line?

I&#39;m starting out in Visual C++ and I&#39;d like to know how to keep the console window.

For instance this would be a typical &quot;hello world&quot; application: 

    int _tmain(int argc, _TCHAR* argv[])
    {
        cout &lt;&lt; &quot;Hello World&quot;;
    	return 0;
    }

What&#39;s the line I&#39;m missing?


How to keep the console window open in Visual C++?

Is there a way to show the console in a Windows application?

I want to do something like this:

    static class Program
    {
        [STAThread]
        static void Main(string[] args) {
            bool consoleMode = Boolean.Parse(args[0]);
    
            if (consoleMode) {
                Console.WriteLine(&quot;consolemode started&quot;);
                // ...
            } else {
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);
                Application.Run(new Form1());
            }
        }
    }

Show Console in Windows Application?

I have a console application that contains quite a lot of threads.  There are threads that monitor certain conditions and terminate the program if they are true.  This termination can happen at any time.

I need an event that can be triggered when the program is closing so that I can cleanup all of the other threads and close all file handles and connections properly.  I&#39;m not sure if there is one already built into the .NET framework, so I&#39;m asking before I write my own.

I was wondering if there was an event along the lines of:

    MyConsoleProgram.OnExit += CleanupBeforeExit;

Capture console exit C#

Like most Python developers, I typically keep a console window open with the Python interpreter running to test commands, `dir()` stuff, `help() stuff`, etc.

Like any console, after a while the visible backlog of past commands and prints gets to be cluttered, and sometimes confusing when re-running the same command several times.  I&#39;m wondering if, and how, to clear the Python interpreter console.

I&#39;ve heard about doing a system call and either calling `cls` on Windows or `clear` on Linux, but I was hoping there was something I could command the interpreter itself to do.

**Note:** I&#39;m running on Windows, so `Ctrl+L` doesn&#39;t work.

How to clear the interpreter console?

I have a `List` that contains all databases names. I have to display the items contained in that list in the Console (using `Console.WriteLine()`). How can I achieve this?



How to display list items on console window in C#

Is there a way to hide the console window when executing a console application?

I am currently using a Windows Forms application to start a console process, but I don&#39;t want the console window to be displayed while the task is running.


How to run a C# console application with the console hidden

How do I find the application&#39;s path in a console application?

In [Windows Forms][1], I can use `Application.StartupPath` to find the current path, but this doesn&#39;t seem to be available in a console application.

  [1]: http://en.wikipedia.org/wiki/Windows_Forms


How can I get the application&#39;s path in a .NET console application?

I just started using ELMAH and am a fan. My team supports a large number of web applications and I&#39;m particularly excited that ELMAH lets us save exceptions from each application to the same MS SQL database table.

We also support a few console, DLL and desktop applications.  Is it possible to use the ELMAH DLL to log exceptions in these apps to that same location?

Using ELMAH in a console application

In .NET, is there a method, such as an event, for detecting when a console application is exiting? I need to clean up some threads and [COM][1] objects.

I am running a message loop, without a form, from the console application.  A [DCOM][2] component that I am using seems to require that the application pump messages.

I have tried adding a handler to Process.GetCurrentProcess.Exited and Process.GetCurrentProcess.Disposed.

I have also tried adding a handler to *Application.ApplicationExit* and *Application.ThreadExit* events, but they are not firing.  Perhaps that is because I am not using a form.

  [1]: https://en.wikipedia.org/wiki/Component_Object_Model
  [2]: https://en.wikipedia.org/wiki/Distributed_Component_Object_Model









.NET console application exit event

ADDED: This question is now, I believe, subsumed by this one:
  &lt;https://stackoverflow.com/questions/1075947/can-i-use-gnu-screen&gt;

See also this related question:  
https://superuser.com/questions/147873/ssh-sessions-in-xterms-freeze-for-many-minutes-whenever-they-disconnect

Original question:

It would be nice if there were a way to ssh to a machine and immediately reconnect to a specific screen session.  You can do this:

    laptop&gt; ssh server.com screen -ls

and it will show a list of screens available on server.com like so [1]:

    123.pts-1
    456.pts-2

And then you might try to do this:

    laptop&gt; ssh server.com screen -dr pts-2

but that fails, saying &quot;Must be connected to a terminal.&quot;
You have to ssh in first and then do the &quot;screen -dr pts-2&quot; on server.com which is no good if you have a flaky connection and get disconnected a lot. You want to be able to resume with a simple &quot;up-arrow enter&quot; on the laptop.  (Or perhaps make it even more automatic.)

I have a rihackulous solution to this problem which I&#39;ll post as an answer and hope it gets downvoted to oblivion in favor of the Right Way to deal with this.

&lt;hr&gt; 
Footnotes:

[1] Or, better, if you created the screen sessions with names like &quot;`screen -S foo`&quot; and &quot;`screen -S bar`&quot; then you&#39;ll get a friendlier list like:

    123.foo
    456.bar

and can reconnect with, eg, &quot;`screen -dr foo`&quot;.

&lt;hr&gt;

## Mini screen tutorial, incorporating the answer to this question:

Login in to server.com and do 

    screen -S foo 

and then never log out of that session again.
To reconnect to it from elsewhere, do

    ssh -t server.com screen -dr foo

To list available screens to reconect to:

    screen -ls

or, of course, 

    ssh server.com screen -ls

to check on server.com&#39;s available screens remotely.

I now use the following alias (tcsh), based on Jason&#39;s answer below, to connect to a named screen if it exists or create and connect otherwise:

    alias ssc &#39;ssh -t \!:1 &quot;screen -S \!:2 -dr || screen -S \!:2&quot;&#39;


Automatically (or more easily) reconnect to a screen session after network interruption

I have a bunch of servers, on which I run experiments using `screen`. The procedure is the following :

 1. `ssh` to server XXX
 2. launch `screen`
 3. start experiments in a few tabs
 4. detach `screen`
 5. disconnect from the server

While the experiments are running, I can easily find on which servers they are by `ssh`ing to all servers and listing my running processes (using `top` or `ps`).

However, once the experiments are finished, how could I find on which servers I have a screen session opened (so that I can have a look at the output, relaunch them, etc.) ?

PS: my experiments do print their output to files, too... but this is not the point of my question.

How to list running screen sessions?

I learned from somewhere a detached screen can be killed by

    screen -X -S [session # you want to kill] kill

where [session # you want to kill] can be gotten from

    screen -ls

But this doesn&#39;t work. Anything wrong? What&#39;s the correct way?

Kill detached screen session

By default, when you create a new window in GNU Screen, it will start in the directory where Screen is invoked. I want to start a new window in GNU Screen at the current working directory of the window I&#39;m currently in. How can I do that?


How can I make GNU Screen start a new window at the CURRENT working directory?

Is it possible to set the Screen Title using a shell script?

I thought about something like sending the key commands &lt;kbd&gt;ctrl&lt;/kbd&gt;+&lt;kbd&gt;A&lt;/kbd&gt; &lt;kbd&gt;shift&lt;/kbd&gt;-&lt;kbd&gt;A&lt;/kbd&gt; `Name` &lt;kbd&gt;enter&lt;/kbd&gt;

I searched for about an hour on how to emulate keystrokes in an shell script, but didn&#39;t find the answer.



Content Type	Original Author	Original Content on Stackoverflow
Question	Francisco Canedo	View Question on Stackoverflow
Solution 1 - Java	Bryce	View Answer on Stackoverflow
Solution 2 - Java	Bart Schuller	View Answer on Stackoverflow
Solution 3 - Java	Jim Blizard	View Answer on Stackoverflow
Solution 4 - Java	DMKing	View Answer on Stackoverflow
Solution 5 - Java	ashes999	View Answer on Stackoverflow

What's a good Java, curses-like, library for terminal applications?

Java Problem Overview

Java Solutions

Solution 1 - Java

Lanterna

Solution 2 - Java

Solution 3 - Java

Solution 4 - Java

Solution 5 - Java

Why are C character literals ints instead of chars?

Design patterns to avoid

Attributions