getTxt（）和SWT Spinner的getSelection（）有什么区别？

Question

For a Spinner control in SWT, what is the difference between getText() and getSelection() ? The only thing I can make out is the return type. However, I cannot enter any text, only numbers are allowed.

getText(): Returns a string containing a copy of the contents of the receiver's text field, or an empty string if there are no contents.

getSelection(): Returns the selection, which is the receiver's position.

So why do we have two different getters and which one should I use?

Answer 1

Since the Spinner represents a numeric selection, you should go with getSelection() as it returns exactly what has been selected.

I don't know why getText() exists, but it'll return the String representation of the selected value, eg if getSelection() returns the int 7 , getText() will return the String "7" .

Answer 2

As the documentation states, getText() returns the string as if is currently displayed, including possible non-numeric values or values outside the min/max range. getSelection() returns the current or last valid integer value.

Usually, you would want to use getSelection() . Does that answer your question?

Answer 3

1. getText specifically says it can be empty (I'd guess it depends on platform whether this ever happens). It then allows to distinguish this case from value 0.

2. You could use getText when using Spinner with decimal digits (see http://help.eclipse.org/luna/topic/org.eclipse.platform.doc.isv/reference/api/org/eclipse/swt/widgets/Spinner.html#setDigits(int) ), since getSelection in this case is farther from the meaning of the value. But note that the decimal separator depends on the current locale.