I know there are a lot of threads about GPS in Android, but I did not find an answer for this. Is it possible to track the position of another android device, and send some information between this two devices only with GPS (with no Internet connection)?
GPS is a one-way information channel from satellites to devices which want to know their own position. There is absolutely no way you can send information via GPS.
If you are looking for direct communication between android devices, your best options are Bluetooth and Wi-Fi Direct.
Sorry, it's simply impossible. No internet connection = no communication.
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What are the ways to connect one gps system to another gps system?. If it is possible then how will be connected without using internet connection?
GPS systems don't send data. They receive data from GPS satellites, but they don't transmit anything. So no, not unless the device the GPS antenna is in has some other way of connecting to another device (wifi, bluetooth, etc). If you're asking about some specific type of GPS device (like Android phones) then there may be a way to do it, but you need to be more specific.
In my flutter app, I need to get information from a device via wifi as a stream. Also I need to keep my google maps online via Mobile internet. How can I use both wifi and mobile network at the same time in my phone. I made a lot of search but I can't find any solution for this.
I don't think it's possible.
The phone would need two network antennas and possibly two network adapters.
You can surely toggle both wifi and mobile data at the same time and they can probably switch frequently to optimize your connection or send requests to different services.
But you can't really use them both at the same time.
(if it's possible) I don't recommend it, since a majority of phones will not support this feature since you need two network antennas.
From the facts as presented, there are a couple of possible solutions, but they aren't perfect and I'm guessing on one as I haven't tested it yet.
One, Google Maps has an offline mode. You can set it up to download maps for offline use. It will show your position on the maps whether you are connected to the internet or not, but you won't get traffic data or accurate travel times. Not great, but it can work.
Two, it is possible for a phone to have a WiFi network and Cellular network active at the same time, but not in the way everyone seemed to think. Since you are wanting the cellular connection open to have access to the internet, I'm assuming this is because the WiFi network you want to access doesn't have the internet. So, reverse the WiFi network. Setup your phone to be a hotspot network, it runs its own WiFi network while maintaining access to the internet through its cellular network. I'm guessing here, but unless phones have some specific security protocol forbidding it I don't know about (which can be the case), your app should be able to contact anything connected to its phone's WiFi while still having access to the internet.
If this doesn't work for some reason, you can try a trick I used when I set up a car office. Get a mobile hotspot device. It's a device you can put a cellular SIMM in and it creates a WiFi hotspot. You can connect to it, along with other devices in the car. All will being using WiFi and the hotspot will provide the internet access.
If what you are connected to can only create a WiFi network for you to access and it can't be configured to connect to one itself, you could technically still be able to do it by network switching. Much harder to do (probably impossible on some devices) and will likely mess with other apps depending on internet access, so a real break glass in case of emergency type of situation there.
My question is that is it possible to send and receive data between multiple android devices via broadcasting over wifi without establishing p2p connection?
Our professor asked us to design a wireless network system in which you broadcast a message within your android phone, and the other android phones nearby receive it and broadcast it again so that the other phones can receive it and it continues like that. In this way, for example, when someone writes a message in a classroom or café everyone will be able to receive it and broadcast it again. (like an adhoc network system). And although my professor believes it can be achievable, I didn't find anything online like this kind of android network system. So my question is again is it possible to do something like that?
Any helpful leads and references will be appreciated.
Edit: I had to change the title of the question.
I couldn't find a proper solution so I tried the following method so far: I set up a UDP messaging app using Wifi hotspot (it works perfectly for multi clients). The phone who turns on the hotspot is the server and others who connect to it are the clients. Then, I decided to turn this system into an adhoc-like system where there would be more than one hotspot and the clients would connect to them in cycling order and serve as a bridge among these servers.(every second, they will switch to other hotspot and vice versa.) So, they will carry the messages from one network to another. (I know it is very inefficient and prone to time delays; but it is the only idea I have come up with so far.)
When I told this system to my professor, he said that it is too complicated and I just need to broadcast a message from a device to a common channel(without setting up a network connection), and other devices will listen to this broadcast channel(without connecting to a network system), receive the message and broadcast their own messages along with received ones to this channel again as I described in the question body. (he never mentions hotspot, Wifi direct, and etc.) He even told me that the only thing I need to do was to think simpler and use the properties of 802.11. But, I do not think it is that easy to set up such a wireless system, at least for Android where ad hoc systems are not supported yet. So any help will be greatly appreciated. Thanks!
The Nearby Connections API in Google Play Services released last week uses WiFi multicast: https://developers.google.com/games/services/android/nearby
It works for devices already on the same WiFi network. However, it uses a host/clients model, and doesn't work with WiFi direct or a tethered hotspot connection.
You could also use the WiFi direct APIs from ICS: https://developer.android.com/guide/topics/connectivity/wifip2p.html
You can have multiple devices connected together via WiFi direct, so firing UDP packets as #willis suggests would seem the way to go
It is implementable. Do you know the aircrack? similarly, you can receive all packets even not sent to you, and you can send any kinds of packets even not sent by you.
Hello I was wondering if anyone could tell me is it possible to read the wifi rssi from another android phone. I am trying to build a simple app that reads the wifi rssi and then uses this to calculate into a distance, I have looked up the WifiManager, TelephonyManager class and the NeighbouringCellInfo, I have even tried to implement a couple of tutorials to no joy. If anyone could point me in the right direction it would be much appreciated.
IMO this will be possible only with Wi-Fi hotspot enable, since this is the only way another phone can see another via Wi-Fi.
If you want to try it out see this thread that helps enabling Wi-Fi hotspot.
Android turn On/Off WiFi HotSpot programmatically
Another thing you might consider is bluetooth RSSI.
Activating bluetooth is more straightforward and can give more precise accuracy (but covers less space).
I am looking to implement a cloud application that allows one to save contacts and if the contact also has the app on, see on a map where the contact is (if in close proximity to you).
I've been looking around towards how to do so and the first step is to establish a connection.
For my purposes, a centralized server to which apps connect and fetch repeatedly updated database information about other users is unsatisfactory as this is too "centralized" for a cloud app.
I've some experience with Bluetooth but in my opinion and experience, bluetooth is not practical as the two devices must then be in very very close proximity with each other.
Thus my question is this, how do android phones connect p2p without the use of local wifi? If that is even possible?
Thank you for your time
Thus my question is this, how do android phones connect p2p without the use of local wifi? If that is even possible?
Yes, via Bluetooth where available, but it will probably not meet your needs. So, in practice, the answer to your question is no. You will need the local wifi.
That being said, you could attempt multicast on the LAN to detect other connected devices enabled with your application. If you want more than LAN, you will need a fully fledge solution including super peers and a P2P framework, like JXTA