Archive for the ‘iTnews’ Category

Serious problem/Bug on Mac OS High Sierra 10.13

November 30th, 2017 Comments off

Today I found a new “bug” on Mac OS High Sierra (10.13). This problem seriously affects to your privacy. What’s that?

When I try to change something from System Preferences, by clicking on the lock icon (on the bottom left corner), then unlock with this login info (User: root Password: left it blank). from here I can change every settings in the system.

Not only the above problem. When restarting the machine, a new “other user” will be displayed on the login screen. like this:














using “root” login info like above.. and then you are now logged in!!! holy shittt




We are still waiting for an official update from Apple to fix this issue. Or below is something you can do to reduce risky possibilities on your system.

To hide “other user” in Login screen, run this following command:

sudo defaults write /Library/Preferences/ SHOWOTHERUSERS_MANAGED -bool FALSE


but.. I believe the better way is to change the default root (administrator) password. check out this link:



Categories: iTnews, mac, macosx, tips, Tips & Tricks Tags:

How to play NES games on MacOS?

March 17th, 2017 1 comment

Hey wasuppp how are you doing guys? I know everything nice today =))

Today I have a look back to Nintendo Entertainment System (NES), some classic games that shaped my childhood, you know “Super mario”? Oh my godness! It’s really amazing that you can actually play most of them in Mac OS (We have another way to play on Windows too!).

The first thing we need to have is OpenEmu (, just go to the link and download it, decompress the archive then copy it to your Application folder on your Mac.

Open it! the appearance would be looks like this:

Screen Shot 2017-03-18 at 00.35.36.png

Next, now we simply find out NES ROMs from internet, for example, I got some ROMs here:

Now from the left side, we choose “Nintendo (NES)”, then drag & drop the downloaded ROMs that you would like to play from this emulator. Then what you can see can be like this after I drag SuperMario to the OpenEmu:

Screen Shot 2017-03-18 at 00.41.46.png

Finally, just double click on it and enjoy your games!

Categories: iTnews, Tips & Tricks Tags:

Why String Class is made Immutable or Final in Java?

February 18th, 2016 No comments


Performance is a reason. But the MAIN REASON is about SECURITY. Are you surprised about this?
OK I’ll let you know..

Suppose you want to open a secured file which require the user authentication. Let’s say there are two users named huynguyen1 and huynguyen2 and they have their own password files password1 and password2, respectively. Obviously huynguyen2 should not have access to password1 file.
As we know the filenames in Java are specified by using String. Even if you create a File object, passing the name of file as a String only and that String is maintained inside the File object as one of its members.

huynguyen1 could have logged into using his credentials and then somehow could have managed to change the name of his password filename (a String object) from password1 to password2 before JVM actually places the native OS system call to open the file. This would have allowed huynguyen1 to open huynguyen2‘s password file.

Understandably, it would have resulted into a big security flaw in Java. I understand there are so many ‘could have’s here, but you would certainly agree that it would have opened a door to allow developers messing up the security of many resources either intentionally or un-intentionally.

With Strings being immutable, JVM can be sure that the filename instance member of the corresponding File object would keep pointing to same unchanged filename String object. The filename instance member being a final in the File class can anyway not be modified to point to any other String object specifying any other file than the intended one (i.e., the one which was used to create the File object).

Huy Nguyen.

Feel free to contact me via email:

Categories: iTnews, Java Tags:

Parse alternative back-end services for you

February 11th, 2016 No comments

As you may noticed Parse will be fully retired after a year-long period ending on January 28, 2017. Most of us need to find an alternative backend service for our apps.

View the list of services on my github, fork it to your account so you can easily find and refer to later.

Categories: iTnews Tags: