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Get total for JTable column  RSS feed

 
Ranch Hand
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I have multiple JSpinner in application as image below.



If the quantity is 1, it will add a new row, if more than 1, the row will be modified. If the quantity is 0 , the row will be removed.
 
How can I subtract the total value if the quantity is decreasing ?

 
Marshal
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Moving to our GUIs forum.
Don't try one Listener listening to several sources. Give each source its own listener class. Is change listener a functional interface? Can you write a λ expression instead?
I can never remember what you do about tables, but I would have thought for something small like that you can recalculate the whole row in the time it takes you to click the arrows on the spinner.
 
Campbell Ritchie
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No, don't write such a switch. Create a Food class which encapsulates price picture and description. Then iterate the row calculating the prices for all items.
 
John Joe
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Is change listener a functional interface?


ChangeListener is an abstract interface that extends java.util.EventListener
 
Campbell Ritchie
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So it is a functional interface. You can shorten that class to λ expressions.
 
John Joe
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Campbell Ritchie wrote:So it is a functional interface. You can shorten that class to λ expressions.

There are multiple spinners in two tabs too which may share the same listener class too . Will it caused a problem? 
 
Campbell Ritchie
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John Joe wrote:. . . There are multiple spinners . . . which may share the same listener class too . Will it caused a problem? . . .

It is not a case of sharing listener classes, but of sharing listener objects. You can have two instances of the same class with different fields which thereby do different things. But it is not usually a good idea to share the same object like that.
 
John Joe
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Campbell Ritchie wrote:No, don't write such a switch. Create a Food class which encapsulates price picture and description. Then iterate the row calculating the prices for all items.

Is this an good idea by writing three different classes for each tab?
 
Sheriff
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John Joe wrote:Is this an good idea by writing three different classes for each tab?



If the other two tabs look just like that one, then I wouldn't write a different class for each tab. I'd have three instances of one class, with different contents. (Just like you might have three instance of the String class with different contents.)
 
John Joe
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Paul Clapham wrote:If the other two tabs look just like that one, then I wouldn't write a different class for each tab. I'd have three instances of one class, with different contents. (Just like you might have three instance of the String class with different contents.)

No,for drinks tab, it contains five image while desserts tab only contains two.
 
Paul Clapham
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John Joe wrote:

Paul Clapham wrote:If the other two tabs look just like that one, then I wouldn't write a different class for each tab. I'd have three instances of one class, with different contents. (Just like you might have three instance of the String class with different contents.)

No,for drinks tab, it contains five image while desserts tab only contains two.



And a String object can contain five characters or only two.
 
John Joe
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I still have no idea on how to iterate the row calculating the prices for all items.
 
John Joe
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I able to solve it in the end. I remove total variable and assign the specific row value to new variables.
 
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