Why Doc Command Cannot Open Documentation Well?

2020 8 24
1 个回答
回答已采纳
更新时间：2020 9 7
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0 个投票

Hi, everyone!
I have an issue with doc command.
So, when I use the following command to call a documentation page on a certain function (for instance, find) like this:
doc find
Instead of opening a window of a documentation page on find function, it calls the MATLAB File Help.
While
doc
will open the desired Documentation Main Page, but when I searched for the function, it failed to brought up results. Instead, the command window displayed some errors:
Exception in thread "com.mathworks.mlwidgets.help.messages.HelpSystemMessageChannel Message Channel Thread": java.lang.NullPointerException
at com.mathworks.search.lucene.LuceneIndexUtils.indexContainsField(LuceneIndexUtils.java:75)
at com.mathworks.helpsearch.DocSearchEngineFactory.createAutoSearchEngine(DocSearchEngineFactory.java:64)
at com.mathworks.help.helpui.search.DocSearchHandler.doSearch(DocSearchHandler.java:58)
at com.mathworks.help.helpui.search.DocSearchHandler.doSearch(DocSearchHandler.java:51)
at com.mathworks.mlwidgets.help.messages.search.DocSearchMessageHandler.handleSearch(DocSearchMessageHandler.java:54)
at com.mathworks.mlwidgets.help.messages.search.DocSearchMessageHandler.handle(DocSearchMessageHandler.java:48)
at com.mathworks.mlwidgets.html.messages.BrowserMessageSubscriber$HelpMessageRunnable.run(BrowserMessageSubscriber.java:110)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
...
When I looked at the Preferences > Help, I found that the Documentation Location is chosen as 'Locally Installed' as a default.
Thus, I changed the preference to 'Web, on mathworks.com (Internet connection required)' as well as selected all products, also tried both choices in Quick Help Display Section.
After those trials, I got
doc
works well and are able to search for functions documentation as usual.
However,
doc find
still open the MATLAB File Help instead of the Documentation page.
...
This has not been an issue in the past. It is only after I reinstalled to add 'System Identification Toolbox' that the problem arises.
Could anyone tell me how to solve this issue? I really enjoy the tidy and clean MATLAB Documentation, so this problem is quite disturbing for me.
As for me, I use MATLAB R2020a, on Windows 7 64-bit, with unrestricted internet access.

4 个评论
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Steven Lord
Steven Lord 2020-8-24
What operating system are you using?
Jan
Jan 2020-8-25
Just a remark: Windows 7 with unrestricted internet access is a really bad idea.
Sorry for possibly misused the network term, since I am a layman in such thing. It is just a normal tethered internet connection from a smartphone, with password.

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 采纳的回答

0 个投票

Hi, everyone.
This problem has been resolved after I reinstall MATLAB R2020a Update 5.
As I tried to uninstall MATLAB using Control Panel, I got an error of missing file in helpsearch folder for Image Processing Toolbox.
I don't know how these files are suddenly lost after I add System Identification Toolbox, but I think this issue may have some connection to the failure of MATLAB Documentation search.

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