Error Message: Error J0051: Undefined Package 'Java.Lang' (171631)


The information in this article applies to:

  • Microsoft Internet Explorer 5.0 for Windows NT 4.0
  • Microsoft Internet Explorer 4.01 for Windows NT 4.0
  • Microsoft Internet Explorer 4.0 for Windows NT 4.0
  • Microsoft Internet Explorer 5.0 for Windows 95
  • Microsoft Internet Explorer 4.01 for Windows 95
  • Microsoft Internet Explorer 4.0 for Windows 95
This article was previously published under Q171631
WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.

SYMPTOMS

When you try to compile a Java class using JVC (Microsoft's Java compiler), you may receive the following error message:
error J0051: Undefined package 'java.lang'

CAUSE

This behavior is caused by the Classes.zip file not being present after you install Internet Explorer.

RESOLUTION

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall Windows. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

NOTE: For information about how to edit the registry, see the online Help in Registry Editor.

To resolve this issue, follow these steps:

  1. Click Start, and then click Run.
  2. Type clspack -auto in the Open box, and then click OK.

    NOTE: This process can take up to two minutes, and during this time no progress indicator is visible.
  3. Try to compile a Java class using JVC. If you are still unable to compile, continue to the next step.
  4. Use Registry Editor to verify that the key listed below is present. If the key is present, verify that it has the value listed below. If needed, edit the value to match the value listed below. If the key is not present, create it with the value shown here.

    HKEY_LOCAL_MACHINE\Software\Microsoft\Java VM\Classpath

    <windir>\java\classes\classes.zip

    Note that <windir> is the folder in which you have Windows 95 or Windows NT 4.0 installed.

MORE INFORMATION

For additional information about how to determine which folder Windows is installed in, click the article number below to view the article in the Microsoft Knowledge Base:

305792 How to Determine Which Folder Windows Is Installed In

Modification Type:MajorLast Reviewed:12/5/2003
Keywords:kberrmsg KB171631
©2003 Microsoft Corporation. All rights reserved.