FULL PRODUCT VERSION :
java version "1.6.0_01"
Java(TM) SE Runtime Environment (build 1.6.0_01-b06)
Java HotSpot(TM) Client VM (build 1.6.0_01-b06, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [Version 5.1.2600]

A DESCRIPTION OF THE PROBLEM :
java.net.URL.openStream() throws java.net.UnknownHostException when java.exe is used. The problem doesn't happen when javaw.exe is used.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Compile the example from Java Tutorial:

import java.net.*;
import java.io.*;

public class URLReader {
  public static void main(String[] args) throws Exception {
    URL yahoo = new URL("http://www.yahoo.com/");
    BufferedReader in = new BufferedReader(
          new InputStreamReader(
          yahoo.openStream()));

    String inputLine;

    while ((inputLine = in.readLine()) != null) {
        System.out.println(inputLine);
    }
    in.close();
  }
}

2. Open Command Prompt.

3. Run it with java.exe:
<JAVA_HOME>\bin\java.exe URLReader > java.log

4. Run again with javaw.exe:
<JAVA_HOME>\bin\javaw.exe URLReader > javaw.log

Result:

java.log is 0 byte. The stack trace is printed on the console when java.exe is used.

javaw.log contains the index.html of www.yahoo.com. There is no stack trace when javaw.exe is used.


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The home page of www.yahoo.com is printed on the console.
ACTUAL -
No output. Stack trace is printed instead.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Exception in thread "main" java.net.UnknownHostException: www.yahoo.com
        at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:177)
        at java.net.Socket.connect(Socket.java:519)
        at java.net.Socket.connect(Socket.java:469)
        at sun.net.NetworkClient.doConnect(NetworkClient.java:157)
        at sun.net.www.http.HttpClient.openServer(HttpClient.java:388)
        at sun.net.www.http.HttpClient.openServer(HttpClient.java:515)
        at sun.net.www.http.HttpClient.&lt;init&gt;(HttpClient.java:233)
        at sun.net.www.http.HttpClient.New(HttpClient.java:306)
        at sun.net.www.http.HttpClient.New(HttpClient.java:318)
        at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLC
onnection.java:792)
        at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConne
ction.java:733)
        at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection
.java:658)
        at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLCon
nection.java:981)
        at java.net.URL.openStream(URL.java:1009)
        at URLReader.main(URLReader.java:7)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.net.*;
import java.io.*;

public class URLReader {
  public static void main(String[] args) throws Exception {
    URL yahoo = new URL("http://www.yahoo.com/");
    BufferedReader in = new BufferedReader(
          new InputStreamReader(
          yahoo.openStream()));

    String inputLine;

    while ((inputLine = in.readLine()) != null) {
        System.out.println(inputLine);
    }
    in.close();
  }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
No known workaround.