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
– Nikhilesh Tiwari, Commented May 23, 2014 at 9:38
What does Preferences > General > Network Connections in Eclipse look like? — johncip
– johncip, Commented May 23, 2014 at 9:45
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
– Nikhilesh Tiwari, Commented May 23, 2014 at 9:58

Duncan Jones · Accepted Answer · 2014-05-23 09:28:38Z

2

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

answered May 23, 2014 at 9:28

Duncan Jones

69.8k32 gold badges204 silver badges262 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Nikhilesh Tiwari Over a year ago

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.

Duncan Jones Over a year ago

@NikhileshTiwari This is the wrong site for help fixing your network issues, I'm afraid.

Pavel Smirnov · Accepted Answer · 2019-04-05 07:41:52Z

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 5, 2019 at 7:41

Pavel Smirnov

4,8293 gold badges22 silver badges32 bronze badges

answered Apr 5, 2019 at 6:38

NevetsKuro

1,0149 silver badges19 bronze badges

Comments

Mohit Kanwar · Accepted Answer · 2014-05-23 09:34:20Z

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, 2014 at 9:34

Mohit Kanwar

3,0708 gold badges41 silver badges61 bronze badges

3 Comments

Nikhilesh Tiwari Over a year ago

I can access the url through my browser but when I am trying to ping the hostname it does not reply back.

Mohit Kanwar Over a year ago

can you check stackoverflow.com/questions/13670692/… If this helps?

Nikhilesh Tiwari Over a year ago

Thanks Code Fighter, I tried changing my program using the solution given but it did not work.

yanyu · Accepted Answer · 2014-05-23 09:44:55Z

0

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

answered May 23, 2014 at 9:44

yanyu

2272 silver badges11 bronze badges

Collectives™ on Stack Overflow

java.net.UnknownHostException:www.google.com

4 Answers 4

2 Comments

Comments

3 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

2 Comments

Comments

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related