I need to connect an android device to my java program via socket connection. The device is working as server. The problem is that while trying out socket connection I need to give IP address and port number of server.
Is there something like a static IP address for an Android device to connect? If not, is there any alternative way to establish a socket connection between the device and my program?
As the device has to have a connection to the same network as the computer, it has to have an IP address configured. So you have to use that one.
The used port is defined by the server application running on your device.
If you have the problem that anyhow a normal network connection is not possible, but you have an ADB connection, you can forward local pots to the device and let your server listen:
http://developer.android.com/tools/help/adb.html#forwardports
Over a mobile connection (GPRS, EDGE, UMTS, HSDPA) there will be no practicable way to establish a connection from somewhere to your device (instead you have to do it the other way, while canceling the whole client-server directive), in cause of the used IP sharing. In that case you have a problem of which I'm not aware if it's possible in general, not to mention how you could achieve this.
Otherwise you simply have to configure a static IP for your device when connected to your local network, or you have to evaluate the actual IP of your device every most of the time, while using it with this configuration:
Resolve it by the device itself
Resolve InetAdress from DhcpInfo
Documentation for DhcpInfo
Resolve by using ADB command
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I am hitting otp api's from Emulator its work but if I am using real device then getting failed to http connecting error found.
2020-11-06 13:33:23.603 24840-24840/a3.amp35.in E/Genrate: failed to connect to /192.168.132.101 (port 80) from /26.81.35.26 (port 39596) after 100000ms
need help
Your device is outside of your local network. Api is on 192.168.132.101 while device is out given net 26.81.35.26
Either expose your API to the outside world (eg. port forward it or host in on globally accessible device) or connect your device to your local network (eg, use the same WIFI, or via VPN)
Also firewall settings on the 192.168.132.101 might block the incoming connections from different subnets.
And probably many more possible causes...
I'm coding an app which consist of two pieces. Desktop and android. There is one desktop and several android devices. (don't know the count.) I want to communicate android devices between desktop with TCP. However, android devices doesn't know desktop's lan ip address.
I thouht 2 ways:
1-Desktop app changes the local ip address on start. So android devices know the ip address. (I coded with that ip address)
2-Desktop app always tries to connect ip addresses (192.168.0.1 - 192.168.0.255) to sent desktop's ip address. And when an android device connect to the network accept the connection then know desktop's ip.
But there is some problems in both ways.
On first, you must be administrator to changing lan ip. So run command as admin with java is a problem. Because if I do this, when user start the program, uac always asks for it.
On second, I think there will be performance issues because of app always tries to connect. Exept this, when android device connect and dhcp gives it 192.168.0.5 , but loop is on 192.168.0.150. So android device have to wait for connection.
Is there a better way than these?
Look at this post Network discovery in Java using multicasting
I think this would be the best way to do it.
The server will listen for a broadcast message from client
the client sends a broadcast request asking for server ip
server receives request and replies back with server ip.
You can use the hostname. If the network is properly configured, the host name will point to the correct ip even if it changes
I recently developed an Android application with which the Android device can communicate with another Android device running the application.
The communication works over sockets, therefore I developed a server which i run on my computer.
Here is my problem:
The communication between the devices over the Server running on my PC works fine, as long as all devices as well as the PC are in the same LAN (connected over the same Router for example).
Now I want to get the server online, so that the Android devices can connect to the "online" server and communicate with each other over the server from anywhere.
I simply have no idea of how to get the server online and running. How can I do that?
The main issue is, that I know about Client/Server communication locally, but have no experience in the "online" sector.
It is more a network problem than a programming one. Your server open a socket and therefore is available to anyone able to reach that socket.
You have to do a redirection on your router. The problem is that your machine doesn't have a public IP, only your router has one. So when your router receive a packet on port 21 for example, it doesn't know what to do with it. You have to configure it to say "the port 21 has to redirected to the local IP XXX"
Also the public IP of your modem/router can change, depending on your ISP. If your have a fixed IP, it won't change, otherwise you will have to install a software like dyndns to have a domain name associated with your IP.
Im using TCP/IP sockets in java to try and create a client-server application. The program works fine when run locally and also over the local area network, but when I use the internet IP address the clients connection is refused.
I used this website to get my IP address and have added a firewall entry to unblock the port im using (port 4445).
I am almost certain the problem lies in some sort of security measure that is blocking the port. Does it matter that I'm running the client and server on the same PC but using the IP address from the previously mentioned website?
If I could get a list of ways to test the port is in fact open, or a list of things to try in order to get my program running, that would be great!
That website may very likely give you the IP address of the gateway through which your PC is connecting to the internet, and if the gateway is out of your control (which is most of the cases as far as I know) there's nothing you can do to use that IP address to test your program. Here's some advice:
Try http://aws.amazon.com, once registered you have one-year free access to a micro-server (which can be accessed publicly through DNS/Elastic IP.)
If your PC have a public IP address, you don't need that website to find out what it is. Just check your network adapter control panel.
Where is the server has been located? If your server is located in some commercial hosting, there is possibility that the ports you use are blocked. Also if you use modem with router or just router in your local network you should check nat table.
Hy! I'm adapting a chat using sockets and threads from java client to android client. The server remains the same. I've wrote the internet and ACCESS_NETWORK_STATE permissions in the manifest. The problem is that when I try to connect to server it throws some errors.
The try{ socket = new Socket("localhost", 5000);} line throws:
link to screenshot
What could be the problem ? Would you want to put the whole code here ?
I'm sure that you're trying to contact your local machine and not the device itself. The phone will address itself using localhost or 127.0.0.1. So when your device is not a server and is not listening for that port the connection will fail.
Try to use 10.0.2.2. This should target your machine you're developing on. (source)
Have you tried using the real network ip of your machine (sth. like 192.168.0.1) instead of "localhost"? The error itself looks to me like there's nobody listening on port 5000. So I guess the Droid is trying to connect to itself instead to the server.