Java Solutions: May 2018

Wednesday, May 30, 2018

Access is denied when ending a task from the task manager

When a program becomes non-responding and you want to kill it, you right click on your task manager to run it as an administrator, find the project, clicked the End Task button and acknowledged the warning message to stop it, you get the following.

You are stuck and is not able to use your program to do anything.

To solve it,

1. Go to the detail tab of your task manager to find the PID of the program.

2. Open your Command Prompt as administrator by right click on it and run as administrator. You can also find the PID of your programs by running the command: tasklist

3. Run the command taskkill as below.

If the above does not work for your, logout and re-login or reboot your computer should solve the problem.

However, the problem still exits even after you have tried to log out and back in and reboot your computer, you may need to restore your computer to a time when it worked.

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Wednesday, May 23, 2018

USB device not recognized: The last USB device you connected to this computer malfunctioned and Windows does not recognize it

You get this message popped up on your screen.

Once you click on it, you see the window below

To fix it, open the control panel and click to open the Device Manager

In the Device Manager window, right click on the Unknown USB Device (Device Descriptor Request Failed), select Uninstall device and acknowledge the warning message to uninstall it. Restart your computer, Windows will reinstall the device automatically.

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Saturday, May 19, 2018

[Solved] Problem Ejecting USB Mass Storage Device: Windows cannot stop your 'Volume' device because a program is still using it

When you try to safely remove your external drive, you get the following message.

You can try the following methods to solve this problem. Among these methods, B and D have always worked for me :)

A. End the program using your external drive through the task manager.

1. Press Ctrl-Alt-Delete at the same time to open the task manager, select the Detail tab, click on the program that is using your external drive. If you cannot identify a program that is using your external drive, select explorer.exe. And then click on the End task button to stop it. If you have selected explorer.exe, continue to finish steps 2 and 3.

2. Click on File in the top menu of the task manager and select Run New Task.

3. Enter Explorer.exe in the popup window and click the OK button.

B. Change the drive letter

1. Open your control panel, go to Control Panel\System and Security\Administrative Tools and open the Computer Management.

2. Right-click on the external drive you want to remove, and select Change Drive Letter and Paths.

3. Select a new and not used letter for this drive and acknowledge the warning message.

4. If you want to continue using the original letter, change it back before you eject your external drive.

C. Clean the clipboard

If you have copied anything from your external drive, chances are that it is still in your clipboard which is like a temporary memory. To clear your clipboard, copy anything that is not part of your external drive or press the print screen key to replace the content in your clipboard.

D. Set your external drive to be removable.

1. Open your Windows Explorer, right-click on your external drive and choose Properties.

2. In the popup window, select the Hardware tab. Click to select your external drive and then click the Properties button.

3. Click the Change settings button in the new popup window.

4. In the new popup window, select the Policies tab and check the Quik Removeal radio button, which will allow you to remove your external drive safely without using the Safely Remove Hardware notification.

5. Click the OK button on all the windows to close them.

Of course, log out and log back in can always help. I hope that you don't need to go so far to shut down your computer. Then, of course, you can unplug the external drive without asking for any permission.

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Tuesday, May 15, 2018

Get the host name and IP address of an Oracle database from sqlplus

A. Through UTL_INADDR

Starting from Oracle 8.1.6, the UTL_INADDR package has been introduced for retrieving host names and IP addresses from PL/SQL. It has two functions: GET_HOST_ADDRESS for querying IP address and GET_HOST_NAME for host name.

SQL> desc UTL_INADDR

FUNCTION GET_HOST_ADDRESS RETURNS VARCHAR2
Argument Name Type In/Out Default?
------------------------------ ----------------------- ------ --------
HOST VARCHAR2 IN DEFAULT

FUNCTION GET_HOST_NAME RETURNS VARCHAR2
Argument Name Type In/Out Default?
------------------------------ ----------------------- ------ --------
IP VARCHAR2 IN DEFAULT

1. Get the host name.

SQL> SELECT UTL_INADDR.get_host_name FROM dual;

GET_HOST_NAME
----------------------------------------
GreatPower

If you know the IP address of the database, you can use that in the query.

SQL> SELECT UTL_INADDR.get_host_name('119.118.1.001') FROM dual;

GET_HOST_NAME('119.118.1.001')
------------------------------------------------
GreatPower

2. Get the IP address

SQL> SELECT UTL_INADDR.get_host_address from dual;

UTL_INADDR.GET_HOST_ADDRESS
------------------------------------------------------------------------
119.118.1.001

If you know the database's host name, you can also use that in the query.

SQL> SELECT UTL_INADDR.get_host_address('GreatPower') from dual;

UTL_INADDR.GET_HOST_ADDRESS('GreatPower')
------------------------------------------------------------------------
119.118.1.001

B. Through SYS_CONTEXT

SQL> SELECT SYS_CONTEXT('USERENV','HOST') as host FROM dual;

HOST
--------------------------------------------------
GreatPower

SQL> SELECT SYS_CONTEXT('USERENV','IP_ADDRESS') as IP FROM dual;

IP
--------------------------------------------------------------
119.118.1.001

C. V$INSTANCE

SQL> SELECT host_name FROM v$instance;

HOST_NAME

----------------------------------------------------------------

GreatPower

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