java.net.UnknownHostException:www.google.com

Question

I am developing a sanity check web application. I tried getting url response using HttpUrlConnection method but I am getting UnknownHostException.

 System.setProperty("java.net.preferIPv4Stack" , "true");
    String[] uat_targetUrls={"https://www.google.com"};
    String[] uat_targetResponse=new String[uat_targetUrls.length];

            HttpURLConnection httpUrlConn;
            httpUrlConn = (HttpURLConnection) new URL(uat_targetUrls[i])
            .openConnection();

            httpUrlConn.setRequestMethod("GET");


            httpUrlConn.setConnectTimeout(30000);
            httpUrlConn.setReadTimeout(30000);



           if(httpUrlConn.getResponseCode()==200)
               uat_targetResponse[i]="UP";
           else 
               uat_targetResponse[i]="DOWN";

When executing this, I am getting UnknownHostException for various urls. Can anyone help me on this. I am using Eclipse IDE. This is the error I am getting:

java.net.UnknownHostException: www.google.com
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)

Thanks.

I am able to access the url through browser but not getting reply from host on ping. — Nikhilesh Tiwari, May 23 '14 at 09:38
What does Preferences > General > Network Connections in Eclipse look like? — johncip, May 23 '14 at 09:45
I can see two sections : Proxy Entries and Proxy ByPass. There are 2 entries in Proxy ByPass->localhost and 127.0.0.1. In Proxy entries HTTP is checked. — Nikhilesh Tiwari, May 23 '14 at 09:58

score 2 · Answer 1 · answered May 23 '14 at 09:28

The problem must be a networking issue on your machine.

Your code works for me (with some minor fixes to repair the missing loop variable i):

public static void main(String[] args) throws Exception {
    System.setProperty("java.net.preferIPv4Stack", "true");
    String[] uat_targetUrls = { "https://www.google.com" };
    String[] uat_targetResponse = new String[uat_targetUrls.length];

    HttpURLConnection httpUrlConn;
    httpUrlConn = (HttpURLConnection) new URL(uat_targetUrls[0])
            .openConnection();

    httpUrlConn.setRequestMethod("GET");

    httpUrlConn.setConnectTimeout(30000);
    httpUrlConn.setReadTimeout(30000);

    if (httpUrlConn.getResponseCode() == 200)
        uat_targetResponse[0] = "UP";
    else
        uat_targetResponse[0] = "DOWN";


    System.out.println(uat_targetResponse[0]);
}

Output: UP

Yeah that works for me too on my local machine. I am facing problem when using it from my organization's desktop. Do you have a fix for this. — Nikhilesh Tiwari, May 23 '14 at 10:10
@NikhileshTiwari This is the wrong site for help fixing your network issues, I'm afraid. — Duncan Jones, May 23 '14 at 10:10

score 1 · Answer 2 · edited Apr 05 '19 at 07:41

1

try pinging www.google.com using

ping www.google.com -t

if you get a time out error
Reason 1: No internet connection
Reason 2: You are probably behind an proxy server.
Reason 3: Add credentials to header

edited Apr 05 '19 at 07:41

Pavel Smirnov

4,611
3
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answered Apr 05 '19 at 06:38

NevetsKuro

604
7
14

score 0 · Answer 3 · answered May 23 '14 at 09:34

0

I tested the code provided by you, It seems working fine. UnknownHostException is thrown when IP address is not resolved. If you are in some organization, check if the network allows you to connect to network through code, or if DNS settings are proper.

answered May 23 '14 at 09:34

Mohit Kanwar

2,962
7
39
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I can access the url through my browser but when I am trying to ping the hostname it does not reply back. – Nikhilesh Tiwari May 23 '14 at 09:41
can you check http://stackoverflow.com/questions/13670692/403-forbidden-with-java-but-not-web-browser If this helps? – Mohit Kanwar May 23 '14 at 09:48
Thanks Code Fighter, I tried changing my program using the solution given but it did not work. – Nikhilesh Tiwari May 23 '14 at 10:11

score 0 · Answer 4 · answered May 23 '14 at 09:44

0

Use ping www.google.com -4 to see if you can visit google.com by ipv4.

answered May 23 '14 at 09:44

yanyu

219
2
11

java.net.UnknownHostException:www.google.com

4 Answers4

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