I want to create a cross platform solution for providing access to the input, error and output streams of a Process in Java.
Basically, what I want to create is a text area that displays the Process' output and error streams, and allows you to supply data to the input stream. In other words, pretty much what Eclipse is already providing with its Console when you run an application.
Now, a basic implementation of this was easy, I simply send all key presses to the input stream. But, of course, I ran into trouble with pasting, backspace and arrow keys, handling ctrl-C and so on.
It seems I should wait before sending data to the Process' input stream. But wait for what? Should I send all entered (and pasted) text at each return key? Or after an interval? What about ctrl-C, ctrl-X and so on. Do I send arrow key movement to the input stream?
The easiest and most user-friendly solution is to have a "Send" button which sends the entire contents of the text area and clears it. Think instant messenger apps or SO comment editor.
You should not wait for anything, simply send - but send in a separate Thread, not your GUI-Event-thread, so the latter one does not block.
For handling the special characters, look what you would get when these signs are entered in a text console.
Related
I am writing simple socket chat using console to output messages. The problem is that when one user types a message, and at the same time getting one, his input interrupted:
I: writing my input here, but
Other_user: hi! here is a message for you.
I: it splits to different lines, which is 1) very inconvenient 2) cannot see which simbols i deleted if press backspace
So, what i am asking is, how can I avoid this
(something like: if message is received, check input for symbols; if there are, remember them, delete last stroke in console, print message, and then recreate that stroke).
EDIT: attached picture
hard to tell without specific code, but an option is to use two threads, one to handle the socket input, one for output. attach these to System.in and System.out respectively. it seems like you might be using only one thread to do both.
I get that this isn't possible to do with normal java, although if there are any libraries out this it would be very useful.
Essentially, I'm designing a console app and running into an issue that when output happens while something is typed in the input line, that input text will move up and appear before the line that just got output. Is it possible to fix this in some form so that the text you are inputting that stays at the bottom?
EX:
I'm typing something as input into my commandline app, and then the program prints something WHILE I'm typing - this causes what was originally on the input line to be scrolled up with whatever the output text was. When you are trying to type something in this can obviously be detrimental. I know it's possible to prevent this.. (Other programs have done it... EX: Minecraft Server)
(If I need to be more descriptive I can.)
You could use the help of threads. One that listens to user input, the other process the actual output. This problem is similar to basic race condition problems when multiple threads attempt to read and write to a shared resource.
Your shared resource is that console. You need to keep the Input/Output operations synchronized. Have a look at race condition.
I am writing a program that takes commands via the console.
However, I do not want to press "enter" in order to send that command.
I want the code to constantly monitor what I am entering, and execute the code when I am finished.
The commands are coming as text from a speech recognition program, therefore, eliminating the need for the "enter" stroke is pretty key.
Any one have any ideas?
I have recently come to the knowledge of events in java and i believe this would help you. You would just need to associate the speech recognition printing to the screen with an event in java and it would have a listener to listen for the event and when it sees the event it would execute your desired code. I currently have a thread opened where im trying to get some good examples of this, perhaps that will help.
Java Events Question
Already answered here:
How to read a single char from the console in Java (as the user types it)?
No portable way to do it, depends on your platform.
I haven't worked with Java since college, but if you're reading from the command line, then you are using System.in.read() or something similar. Since these are blocking method calls, your application will never be notified about the new input until ENTER is pressed.
If I'm dead wrong, please let me know.
You're probably better off using a simple (possibly even hidden) that can take the user text and an event listener on the UI element that reads it in to the application's text processor.
I want to add a "history" function to my java programm, like known from bash etc, so pressing the arrow keys should show previous send commands.
It's no problem to write the past commands to the default output, which will in three new lines if arrow up is hit three times and in not editable output. I want the output of the programm to be written in the input field so i just have to hit enter, to resend the command.
Is this possible?
Kind Regards
Take a look at JLine, which provides command history, tab completion and line editing.
If you want to roll your own solution, this will get you started.
You want to change from using a buffered input into a direct input. You can do this by interfacing with System.in directly. You should create a thread to handle this, and have it block on a call to System.in.read() in a loop, reading one byte at a time.
Each time a byte is read, keep your own buffer updated with the current command that's being read. Every character that gets typed, add it to the buffer. If the character is a \b, delete the last character in the buffer. When you detect a \r or \n, execute the command in the buffer and clear it.
If you receive an up or down arrow, send a number of \bs to System.out equal to the length of the buffer. This will erase the local copy of any current command being entered. Then print out the new command to System.out and enter it into the buffer, replacing whatever was there. This will allow the user to delete it, add to it, or just press enter to submit it. This mimics the functionality of bash.
You can also detect a \t (tab) character and implement a tab-completion function.
I want to send a barcode, read with my cellphone, to my computer. My computer has a simple server running, which listens to barcodes. When a barcode arrives, the server app should be able to input the value of the received barcode into the active application (I don't really care which application is going to get the input, the user should be able to select gedit, a terminal window or the browser if they choose to).
My language at the moment is Java on GNU/Linux (Ubuntu), so I know about the Robot class. But the Robot class emulates a keyboard, which means: when you send VK_1 on a US keyboard layout, the output is '1' indeed, but when you send VK_1 on another layout (like belgian, which I use), which requires shift for the '1' key, the output is '&' (this is the character on the '1' key, when you don't hold shift).
I also found xsendkeys, but this application too requires you to specify whether you need to hold shift. So it will be able to send an 'a' but for an 'A' (thus capital) you need to specify you want to hold shift with your 'a'.
Isn't there an easy way to do this, for GNU/Linux and Windows, just using strings. I want to be able to send "12a68dd" to the active application. And I also would like to be able to send UTF-8 characters to the active application.
I have been looking for a solution, but most require the breakdown in multiple keystrokes, which are often dependent on the keyboard layout.
Seems like you want to be able to send an arbitrary keyboard sequence to any possible application. With that I cannot help you (you should look for "Java UI testing automation" to find any suitable tools), but if the application you are sending the string to listens for it on its standard input, I would go for:
// Example: send your string to "cat" (or "type" on Windows), which simply prints it.
Process spawned = ProcessBuilder.command("cat" /*No arguments*/).start();
spawned.getOutputStream().write(yourString.getBytes("UTF-8"));
Simple stdin/stdout redirection, in other words.
If I understand you correctly, you wish to send a series of characters into another application (the destination). This destination could be any application, and you may not have access to its source code.
The answer is simply no.
Key strokes differ to characters (which I gather you have probably worked out) and Robot was intended just to invoke key strokes. The resulting output of those key strokes is generally different due to the fact most keyboards used do not follow the ISO standard for keyboards.
There are often other ways of accomplishing the same affect though, through APIs, file IO, etc.
I may not have grasped your question completely, but you want to separate applications, both written in Java, to exchange information? I'd recommend you read up on RMI, which exists för that very purpose.
Just wanted to let you know my sollution:
Call xvkbd -text from java and give the text to be writen as argument. If the text contains spaces, I call xvkbd multiple times with a xvkbd -text \[space] call within.
My current way is pretty easy to 'port' to windows, so that wont be too hard to get running with a SendKeys VB application.
Thanks all for your help!