Norm Radder

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since Aug 10, 2005
Worked mostly with IBM mainframe assembly code. Loved IBM's VM OS.
Eastern Florida
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Recent posts by Norm Radder

Thanks for the recommendations and observations.

I'be been looking at multicast, but as Tim suggests, that protocol could be locked down.
Here's some testing code I've used:


The next idea is to use the IP addresses for the two tablets that are assigned on connecting to the LAN.  They can be swapped at the start of the day and then with some scheduling could be used during the day to communicate.
The design has taken another turn.  I found an app in Google Store that does most of what I want:  Lan Messanger
However I'm having timeout/disconnect problems with it.  Also I'd like it to make a sound (ring a bell) when it gets a special message.
So the new project is an app to listen and ring a bell when connected to. Otherwise it still is to run P2P on a LAN.
When the bell rings, the receiver would start the Lan Messenger program to have a chat session.

One problem is to find the other tablet.  I found some code on SO and modified it to to the search:
https://stackoverflow.com/questions/39335835/how-to-get-ip-address-and-names-of-all-devices-in-local-network-on-android

Create a simple store-and-forward webapp. An Android client app could easily invoke this as a web service.  


I'll have to do some research.  I have no idea what the specifics of that means.

My simple HTTP server handles GET and POST.
https://github.com/NormR/Android-Simple-Web-Server
Security isn't an issue.
The messages would be like this:
Will be late.  Meet you on Stbd side at 1145
or
Free drinks at TiKi-bar until noon.  See you there at 1130
Ok, will be there
Thanks for the responses.

My app was to allow my wife and I to communicate from anywhere in the ship using the ship's LAN.

require the devices to connect to an access point.

Yes, we use the ship's LAN which is free.
It is possible to connect to the ship's LAN without then going on to the internet.  I have a simple HTTP server app that I use to transfer files using the app on one tablet and a browser on the other.


do you really need to communicate digital?


Yes.  We have different events we attend at different locations and times.  It would be nice to tell the other one if there is a delay or rescheduling of an event.

And this looks like an interesting project for my Android toolkit.
I'm looking at a project for a P2P program that would allow two computers (tablets) to communicate on a LAN without the internet.
My assumptions/ideas so far:
The computers can connect to the LAN.
For P2P to work both computers need to have ServeSockets and use a Socket to connect to the other computer.
There needs to be a discovery/search feature that allows the program to find the other program amoungst all the other computers that are connected to the LAN.  If the computers always get the same IP address every time they connect, finding the other computer would be a lot simpler.
The computers would need to connect to the LAN and wait for the other computer to connect to its ServerSocket.  No idea how much battery this would take.
The basic code should be the same on a PC as on the tablet.  The differences would be in the GUI and perhaps the services available on he tablet.

Does anyone have thoughts, ideas or examples for this project?


Background:  My wife and I travel on cruise ships that provide a LAN with several free services and pay-for internet access.
We both have Android tablets.  We do not buy the internet access.
I wonder if it would be possible to send messages to each other using the LAN.

I just finished a WiFi-Direct program for our tablets (based on an example from a Google samples site).  The basic discovery part is done by the OS.  It defines an IP address and decides which tablet is the server and which the client.  The program then opens a ServerSocket on the server and uses a Socket from the client to connect to the server.  After that it is up to whatever protocol you want to write.
What is the contents of the variable: results that is passed to the method?
2 weeks ago
I'm trying to write a javascript slideshow (yes another one) to show images listed in a .js file.  The images are a mix of landscape and portrait layouts.  I am having a problem keeping the portrait images from overflowing the browser's display area and making it necessary to scroll to see the full image.  Is there a way in javascript and css to keep the images within the browser's viewing area?
Here's one of my many attempts:


Also posted here: https://www.dreamincode.net/forums/topic/416918-prevent-portrait-images-from-overflowing-screen/

Exception in thread "main" java.lang.StackOverflowError
   at project1.Project1.quicksort(Project1.java:43)
   at project1.Project1.quicksort(Project1.java:47)


Looks like there is a recursive call at line 47.  Can you post the code that shows lines 43 and 47
4 weeks ago
Look at the code and see where those lines are printed.
Is it inside of a loop? What variables control if that loop continues looping?
What conditional test controls if the loop continues?
4 weeks ago

The problem is the Transportation Menu is repeating after I make a selection.


Can you post the program's output that shows the problem?  Be sure to add some comments where the program's output goes wrong.
4 weeks ago

I'm not quite sure where the problem is  


Where is there any problem?
Is that output what you want the program to do?  
I asked for some comments (<<<< This is wrong because ...) be added to the output to point out to us where the problem is  I don't see any comments like that so I assume the output is correct.
4 weeks ago

it coudn't compile
... reasons causing this problem
1) my program doesnt have main method,


A class does NOT need a main method to compile.  There shouldn't be any compiler errors for a class because it does not have a main method.

A class usually needs a main method to be executed with the java command.  There are a few exceptions.
1 month ago
Can you copy the contents of the console window and paste it here so we can see what is happening?

Add some comments (<<<< Here it repeats) to show where the problem is.
1 month ago