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General Java Questions I
to the specified position of the destination array. A subsequence of array components
are copied from the source array referenced by src to the destination array
referenced by dst. The number of components copied is
equal to the length argument. The components at positions srcOffset through
srcOffset+length-1 in the source array are copied into positions dstOffset through
dstOffset+length-1, respectively, of the destination array.
If the src and dst arguments refer to the same array object, then the copying is
performed as if the components at positions srcOffset through srcOffset+length-1
were first copied to a temporary array with length components and then the contents
of the temporary array were copied into positions dstOffset through
dstOffset+length-1 of the argument array."
Q: More about Robot! I met with a problem in using class Robot.mousePress...
The compiling process is successful. But when I run it, I receive
"IllegalArgumentException:
Invalid combination of button flags". I don't quit understand this information. Part of
my code is as following:
Robot rMouse=new Robot();
int button=1;
rMouse.mousePress(button);
rMouse.mouseRelease(button);
I am really confused. Will you please give me some advice? Thank you in advance!
Answer: You are not using a valid value for the argument to the mousePress() and
mouseRelease() methods. If you check the API documentation, you'll find the valid
values are a combination of one or more of the following constants:
InputEvent.BUTTON1_MASK
InputEvent.BUTTON2_MASK
InputEvent.BUTTON3_MASK
plus others which represent the Ctrl, Alt, and Shift keys. To press the left
mouse button, you want to use:
rMouse.mousePress(InputEvent.BUTTON1_MASK);
--
Lee Weiner
Q: In what situation an exception has to be caught otherwise the compiler will
complain?
e.g. IOException does NOT have to be explicitly caught, however, SQLException has
to be caught otherwise VisalAge will not compile the program.
Answer: The only unchecked exceptions in Java are RuntimeException and its
subclasses. This includes such familiar classes as NullPointerException,
ClassCastException, and IndexOutOfBoundsException.
IOException is not one of these, and *does* have to be explicitly caught or thrown
-jeff_robertson
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