Re: [jnc-users] NullPointerException in HTTPUrlConnection

[A. 's. A. <str...@gm...>]

Marco, catching the NPE will prevent the crash in c.connect(), but the
application starts to behave strangely, and then just segfaults. I found a
workaround, you can add this line:

            InetAddress addr = InetAddress.getByName(new URL("
http://bogusurl/asdf/").getHost());

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>
>>    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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>>
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>
>