java net UnknownHostException Invalid hostname for server local

Question

What are the steps I should take to solve the error   java net UnknownHostException  Invalid hostname for server  local   I added the new virtual host name at Android emulator but the result returns to   java net UnknownHostException virtualhostname at    java net InetAddress lookUpHostByName InetAddress java 506    When I type my virtualhost URL on my PC  it works on display  Then again  when I ran on Emulator and check on Logcat  I couldn t be able to read or check the HTTP status if 200  202  or an error code number  It simply returned to UnknownHostException

User · Answer

This might happen due to various reasons

1) Check if you have VPN connected, you might get this error sometimes if yes

"Your hostname, localhost resolves to a loopback address: 127.0.0.1; using 10.xxx.1.193 instead (on interface cscotun0)"

2) Check your $HOSTNAME

3) try to ping $HOSTNAME on commandline and if it doesnt work, tweak the system settings to make your local host respond to pings

User · Answer

If your  etc localhosts file has entry as below  Add hostname entry as below   127 0 0 1 local host  add your hostname here    1  add hostname here   the last one is IPv6     This should resolve the issue

User · Answer

I had this issue in my android app when grabbing an xml file the format of my link was not valid  I reformatted with the full url and it worked

User · Answer

Try the following    String url    http   www google com search q java   URL urlObj    URL new URL url trim     HttpURLConnection httpConn     HttpURLConnection urlObj openConnection    httpConn setRequestMethod  GET    Integer rescode   httpConn getResponseCode    System out println rescode     Trim   the URL

User · Answer

Please try to set SPARK LOCAL IP environment variable to the ip address can be localhost i e  your own ip address  you want to connect  E g        export SPARK LOCAL IP 182 95 208 152    This way you will not be required to alter existing linux settings  Worked for me  hope helps you too

User · Answer

If you are here because your emulator gives you that Exception  Go to Tools   AVD Manager in your android emulator and Cold boot your Emulator

User · Answer

java net UnknownHostException  Host is unresolved    Thrown to indicate that the IP address of a host could not be determined   This exception is also raised when you are connected to a valid wifi but router does not receive the internet  Its very easy to reproduce this    Connect to a valid wifi Now remove the cable from the router while router is pluged-in   You will observe this error    You can t really solve this  You can only notify the user gracefully   something like -  Unable to make a connection

User · Answer

I was having the same issue on my mac  I found the issue when I pinged my  HOSTNAME from terminal and it returned ping  cannot resolve myHostName  Unknown host    To resolve    Do echo  HOSTNAME on your terminal  Whatever hostname it shows  lets say myHostName   try to ping it   ping myHostName  If it returns ping  cannot resolve myHostName  Unknown host then add an entry into your  etc hosts file  For that edit  etc hosts file and add following   127 0 0 1        myHostName   Hope it helps

User · Answer

Trying to connect to your local computer try with the hostname  localhost  instead or perhaps     - the last one is ipv6

User · Answer

Connect your mobile with different wifi connection with different service provider   I don t know the exact issue but i could not connect to server with a specific service provider but it work when i connected to other service provider  So try it

User · Answer

This is not specific to the question  but this question showed up when I was Googling for the mentioned UnknownHostException  and the fix is not found anywhere else so I thought I d add an answer here   The exception that was continuously received was   java net UnknownHostException   google com     at java net AbstractPlainSocketImpl connect AbstractPlainSocketImpl java 184      at java net SocksSocketImpl connect SocksSocketImpl java 392      at java net Socket connect Socket java 589      at java net Socket connect Socket java 538      at java net Socket  lt init gt  Socket java 434      at java net Socket  lt init gt  Socket java 211             No matter how I tried to connect to any valid host  printing it in the terminal would not help either  Everything was right   The Solution  Not calling trim   for the host string which contained whitespace  In writing a proxy server the host was obtained from HTTP headers with the use of split      by semicolons for the HOST header  This left whitespace  and causes the UnknownHostException as a host with whitespace is not a valid host  Doing a host   host trim   on the String host solved the ambiguous issue

User · Answer

What the exception is really saying is that there is no known server with the name  local   My guess is that you re trying to connect to your local computer  Try with the hostname  localhost  instead  or perhaps 127 0 0 1 or   1  the last one is IPv6    From the javadocs      Thrown to indicate that the IP address   of a host could not be determined    127 0 0 1or   1 or  localhost  should always be the loopback interface  so if that doesn t work I d be really surprised   If there really is a server called  local  on your network - examine your DNS settings or add it to your hosts file

User · Answer

Your hostname is missing   JBoss uses this environment variable   HOSTNAME  when it connects to the server    root xyz     echo  HOSTNAME xyz   root xyz     ping  HOSTNAME ping  unknown host xyz   root xyz     hostname -f hostname  Unknown host   There are dozens of things that can cause this   Please comment if you discover a new reason   For a hack until you can permanently resolve this issue on your server  you can add a line to the end of your  etc hosts file   127 0 0 1 xyz xxx xxx edu xyz

[java] java.net.UnknownHostException: Invalid hostname for server: local

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