Re: [jnc-users] NullPointerException in HTTPUrlConnection

[Marco T. <ma...@mt...>]

Hello André

André 'streeto' Amorim wrote:
> Marco, catching the NPE will prevent the crash in c.connect(), but the 
> application starts to behave strangely, and then just segfaults.

Whew! In this case there's a serious problem, not just a non-Sun-JRE 
behavior as I suspected.

> I found 
> a workaround, you can add this line:
> 
>             InetAddress addr = InetAddress.getByName(new 
> URL("http://bogusurl/asdf/").getHost());

Great, thank you!


Marco


> This will cause an UnknownHostException if the host is unreachable. The 
> snippet I sent before becomes, then,
> 
> import java.net.InetAddress;
> import java.net.URL;
> import java.net.URLConnection;
> 
> public class URLConnectionTest {
>     static public void main(String[] args) {
>         try {
>             System.out.println("first try");
>             URL u = new URL("http://www.hasdklashdklj.com/");
>             System.out.println(u);
>            
>             // HACK (GCJ): will throw an UnknownHostException if host is 
> unreachable.
>             @SuppressWarnings("unused")
>             InetAddress addr = InetAddress.getByName(u.getHost());
>            
>             URLConnection c = u.openConnection();
>             System.out.println(c);
>             c.connect();
>             System.out.println("done");
>         } catch (Exception e) {
>             System.out.println("nono");
>             e.printStackTrace();
>         }
>     }
> }
> 
> Hope this helps.
> 
> André.
> 
> On Tue, Jul 15, 2008 at 11:24 AM, Marco Trudel <ma...@mt...> wrote:
> 
>     Hello André
> 
>     André 'streeto' Amorim wrote:
> 
>         Hi, I just had the same problem Avi Cohen reported a couple
>         months ago. Using a url that does not exist leads to a NPE. The
>         code I used for testing is almost the same:
> 
>         import java.net.URL;
>         import java.net.URLConnection;
> 
>         public class URLConnectionTest {
>            static public void main(String[] args) {
>                try {
>                    URL u = new URL("http://www.hasdklashdklj.com/");
>                    System.out.println(u);
>                    URLConnection c = u.openConnection();
>                    System.out.println(c);
>                    c.connect();
>                    System.out.println("done");
>                } catch (Exception e) {
>                    System.out.println("nono");
>                    e.printStackTrace();
>                }
>            }
>         }
> 
>         Here's the setup:
> 
>         JNC-1.1.1
>         gcc-122233
>         Using Windows XP
>         Compiling for Windows
>         Compiling from source
>         Config:
>         Not excluding JCE
>         Not optimizing
>         Not stripping
>         Not packing
>         All the other options are the default  (new project)
> 
>         Here's the output:
> 
>         A. exclude JCE, add GNU regex
> 
>         http://www.hasdklashdklj.com/
>         nono
>         java.lang.NullPointerException
>           at
>         java.net.URLConnection.toString(/usr/local/src/gcc/libjava/classpath/java/net/URLConnection.java:627)
>           at
>         java.io.PrintStream.println(/usr/local/src/gcc/libjava/java/io/PrintStream.java:473)
>           at
>         URLConnectionTest.main(C:/DOCUME~1/andre/CONFIG~1/Temp/ccOsbaaa.jar:0)
> 
> 
>         B. not excluding JCE, not adding GNU regex (does not seem to
>         interfer, tried with and without)
> 
>         http://www.hasdklashdklj.com/
>         gnu.java.net.protocol.http.HTTPURLConnection:http://www.hasdklashdklj.com/
>         nono
>         java.lang.NullPointerException
>           <<No stacktrace available>>
> 
> 
>         The output in eclipse is
> 
>         http://www.hasdklashdklj.com/
>         sun.net.www.protocol.http.HttpURLConnection:http://www.hasdklashdklj.com/
>         nono
>         java.net.UnknownHostException: www.hasdklashdklj.com
>         <http://www.hasdklashdklj.com> <http://www.hasdklashdklj.com>
> 
>            at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:177)
>         (...)
> 
> 
>         Anybody has a workaround? I can't find a way to check the URL
>         without using URL.openConnection().
> 
> 
>     maybe:
>     try { ... } catch(NullPointerException ex) { /* illegal url */ }
>     ?
> 
> 
>     Marco
> 
>         []s
> 
>         André.
> 
> 
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