Java: How can I check an observable list in Java to make sure it contains at least one value before...
I am fairly new at Java, doing a class project where I need to make a user interface using Java FXML for a company inventory system and then make it workable. I have parts and products that are added, deleted, modified, etc. Each product has a variety of parts and when you modify the product you can add/delete parts. There must be at least one part in the product at all time.
I have a table that represents all of the parts in a particular product, and I need to modify it to where it will not delete a part if it's the only part in the observable list for that product.
Currently I'm using the below to delete the parts which works fine, but obviously does not stop me from fully deleting. I was thinking that using the is.Empty method might help because if it's empty, I can pop up an error saying 'you must have at least one part'. However I'm having trouble implementing that. I was also thinking a while or if/then statement could be useful, because I could just put the segment for deleting inside the while or if/then loop with the condition the observable list isn't empty and the error in the case it is, but I'm not totally sure how I would implement that either and haven't found any resources within my textbooks. I was hoping for a pointer in the right direction, or advice if I'm just completely looking at it the wrong way.
selectedProduct.getAssociatedPart().remove(partsinproduct.getSelectionModel().getSelectedItem());
java observablelist
asked Nov 15 '18 at 19:49
CassieCassie
11
add a comment |
I am fairly new at Java, doing a class project where I need to make a user interface using Java FXML for a company inventory system and then make it workable. I have parts and products that are added, deleted, modified, etc. Each product has a variety of parts and when you modify the product you can add/delete parts. There must be at least one part in the product at all time.
I have a table that represents all of the parts in a particular product, and I need to modify it to where it will not delete a part if it's the only part in the observable list for that product.
Currently I'm using the below to delete the parts which works fine, but obviously does not stop me from fully deleting. I was thinking that using the is.Empty method might help because if it's empty, I can pop up an error saying 'you must have at least one part'. However I'm having trouble implementing that. I was also thinking a while or if/then statement could be useful, because I could just put the segment for deleting inside the while or if/then loop with the condition the observable list isn't empty and the error in the case it is, but I'm not totally sure how I would implement that either and haven't found any resources within my textbooks. I was hoping for a pointer in the right direction, or advice if I'm just completely looking at it the wrong way.
selectedProduct.getAssociatedPart().remove(partsinproduct.getSelectionModel().getSelectedItem());
java observablelist
asked Nov 15 '18 at 19:49
CassieCassie
11
add a comment |
I am fairly new at Java, doing a class project where I need to make a user interface using Java FXML for a company inventory system and then make it workable. I have parts and products that are added, deleted, modified, etc. Each product has a variety of parts and when you modify the product you can add/delete parts. There must be at least one part in the product at all time.
I have a table that represents all of the parts in a particular product, and I need to modify it to where it will not delete a part if it's the only part in the observable list for that product.
Currently I'm using the below to delete the parts which works fine, but obviously does not stop me from fully deleting. I was thinking that using the is.Empty method might help because if it's empty, I can pop up an error saying 'you must have at least one part'. However I'm having trouble implementing that. I was also thinking a while or if/then statement could be useful, because I could just put the segment for deleting inside the while or if/then loop with the condition the observable list isn't empty and the error in the case it is, but I'm not totally sure how I would implement that either and haven't found any resources within my textbooks. I was hoping for a pointer in the right direction, or advice if I'm just completely looking at it the wrong way.
selectedProduct.getAssociatedPart().remove(partsinproduct.getSelectionModel().getSelectedItem());
java observablelist
asked Nov 15 '18 at 19:49
CassieCassie
11
I am fairly new at Java, doing a class project where I need to make a user interface using Java FXML for a company inventory system and then make it workable. I have parts and products that are added, deleted, modified, etc. Each product has a variety of parts and when you modify the product you can add/delete parts. There must be at least one part in the product at all time.
I have a table that represents all of the parts in a particular product, and I need to modify it to where it will not delete a part if it's the only part in the observable list for that product.
Currently I'm using the below to delete the parts which works fine, but obviously does not stop me from fully deleting. I was thinking that using the is.Empty method might help because if it's empty, I can pop up an error saying 'you must have at least one part'. However I'm having trouble implementing that. I was also thinking a while or if/then statement could be useful, because I could just put the segment for deleting inside the while or if/then loop with the condition the observable list isn't empty and the error in the case it is, but I'm not totally sure how I would implement that either and haven't found any resources within my textbooks. I was hoping for a pointer in the right direction, or advice if I'm just completely looking at it the wrong way.
selectedProduct.getAssociatedPart().remove(partsinproduct.getSelectionModel().getSelectedItem());
java observablelist
java observablelist
asked Nov 15 '18 at 19:49
CassieCassie
11
asked Nov 15 '18 at 19:49
CassieCassie
11
asked Nov 15 '18 at 19:49
CassieCassie
11
asked Nov 15 '18 at 19:49
CassieCassie
11
asked Nov 15 '18 at 19:49
CassieCassie
11
11
add a comment |
add a comment |
1 Answer
1
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I think, a little bit simplified, the problem will look like
list.remove(elem);
... but do it only, if elem is not the only element in the list.
This is the code for doing it:
if (list.size() > 1)
list.remove(elem);
When there is only one element in the list, you must not remove it. Without the if it would only be removed if it would match. In an empty list you cannot remove the element anyway. When there are two or more elements in the list, you are allowed to remove.
answered Nov 15 '18 at 20:54
DonatDonat
848128
Thanks for your answer! Does list.size work for an observable list as well? I am trying to implement that using the name of my observable list or using observablelist.size but i'm getting errors in running it.
– Cassie
Nov 15 '18 at 21:51
It depends on what you want to check. I assumed that the list is an object of some class that implements the interfaceList. If does not depend on what is in the list. But be aware that the elements'equals()method. will be used to identifiy the element to be removed withlist.remove. For the list ofObserverin anObservable, use its methodscountObserversanddeleteObserver.
– Donat
Nov 15 '18 at 22:28
Thank you for your help! I'm going to read read up on the methods you mentioned as they aren't ones I'm super familiar with at this point and I am eager to understand them more.
– Cassie
Nov 15 '18 at 23:02
add a comment |
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1 Answer
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1 Answer
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I think, a little bit simplified, the problem will look like
list.remove(elem);
... but do it only, if elem is not the only element in the list.
This is the code for doing it:
if (list.size() > 1)
list.remove(elem);
When there is only one element in the list, you must not remove it. Without the if it would only be removed if it would match. In an empty list you cannot remove the element anyway. When there are two or more elements in the list, you are allowed to remove.
answered Nov 15 '18 at 20:54
DonatDonat
848128
Thanks for your answer! Does list.size work for an observable list as well? I am trying to implement that using the name of my observable list or using observablelist.size but i'm getting errors in running it.
– Cassie
Nov 15 '18 at 21:51
It depends on what you want to check. I assumed that the list is an object of some class that implements the interfaceList. If does not depend on what is in the list. But be aware that the elements'equals()method. will be used to identifiy the element to be removed withlist.remove. For the list ofObserverin anObservable, use its methodscountObserversanddeleteObserver.
– Donat
Nov 15 '18 at 22:28
Thank you for your help! I'm going to read read up on the methods you mentioned as they aren't ones I'm super familiar with at this point and I am eager to understand them more.
– Cassie
Nov 15 '18 at 23:02
add a comment |
I think, a little bit simplified, the problem will look like
list.remove(elem);
... but do it only, if elem is not the only element in the list.
This is the code for doing it:
if (list.size() > 1)
list.remove(elem);
When there is only one element in the list, you must not remove it. Without the if it would only be removed if it would match. In an empty list you cannot remove the element anyway. When there are two or more elements in the list, you are allowed to remove.
answered Nov 15 '18 at 20:54
DonatDonat
848128
Thanks for your answer! Does list.size work for an observable list as well? I am trying to implement that using the name of my observable list or using observablelist.size but i'm getting errors in running it.
– Cassie
Nov 15 '18 at 21:51
It depends on what you want to check. I assumed that the list is an object of some class that implements the interfaceList. If does not depend on what is in the list. But be aware that the elements'equals()method. will be used to identifiy the element to be removed withlist.remove. For the list ofObserverin anObservable, use its methodscountObserversanddeleteObserver.
– Donat
Nov 15 '18 at 22:28
Thank you for your help! I'm going to read read up on the methods you mentioned as they aren't ones I'm super familiar with at this point and I am eager to understand them more.
– Cassie
Nov 15 '18 at 23:02
add a comment |
I think, a little bit simplified, the problem will look like
list.remove(elem);
... but do it only, if elem is not the only element in the list.
This is the code for doing it:
if (list.size() > 1)
list.remove(elem);
When there is only one element in the list, you must not remove it. Without the if it would only be removed if it would match. In an empty list you cannot remove the element anyway. When there are two or more elements in the list, you are allowed to remove.
answered Nov 15 '18 at 20:54
DonatDonat
848128
I think, a little bit simplified, the problem will look like
list.remove(elem);
... but do it only, if elem is not the only element in the list.
This is the code for doing it:
if (list.size() > 1)
list.remove(elem);
When there is only one element in the list, you must not remove it. Without the if it would only be removed if it would match. In an empty list you cannot remove the element anyway. When there are two or more elements in the list, you are allowed to remove.
answered Nov 15 '18 at 20:54
DonatDonat
848128
answered Nov 15 '18 at 20:54
DonatDonat
848128
answered Nov 15 '18 at 20:54
DonatDonat
848128
answered Nov 15 '18 at 20:54
DonatDonat
848128
848128
Thanks for your answer! Does list.size work for an observable list as well? I am trying to implement that using the name of my observable list or using observablelist.size but i'm getting errors in running it.
– Cassie
Nov 15 '18 at 21:51
It depends on what you want to check. I assumed that the list is an object of some class that implements the interfaceList. If does not depend on what is in the list. But be aware that the elements'equals()method. will be used to identifiy the element to be removed withlist.remove. For the list ofObserverin anObservable, use its methodscountObserversanddeleteObserver.
– Donat
Nov 15 '18 at 22:28
Thank you for your help! I'm going to read read up on the methods you mentioned as they aren't ones I'm super familiar with at this point and I am eager to understand them more.
– Cassie
Nov 15 '18 at 23:02
add a comment |
Thanks for your answer! Does list.size work for an observable list as well? I am trying to implement that using the name of my observable list or using observablelist.size but i'm getting errors in running it.
– Cassie
Nov 15 '18 at 21:51
It depends on what you want to check. I assumed that the list is an object of some class that implements the interfaceList. If does not depend on what is in the list. But be aware that the elements'equals()method. will be used to identifiy the element to be removed withlist.remove. For the list ofObserverin anObservable, use its methodscountObserversanddeleteObserver.
– Donat
Nov 15 '18 at 22:28
Thank you for your help! I'm going to read read up on the methods you mentioned as they aren't ones I'm super familiar with at this point and I am eager to understand them more.
– Cassie
Nov 15 '18 at 23:02
Thanks for your answer! Does list.size work for an observable list as well? I am trying to implement that using the name of my observable list or using observablelist.size but i'm getting errors in running it.
– Cassie
Nov 15 '18 at 21:51
Thanks for your answer! Does list.size work for an observable list as well? I am trying to implement that using the name of my observable list or using observablelist.size but i'm getting errors in running it.
– Cassie
Nov 15 '18 at 21:51
It depends on what you want to check. I assumed that the list is an object of some class that implements the interface
List. If does not depend on what is in the list. But be aware that the elements' equals() method. will be used to identifiy the element to be removed with list.remove. For the list of Observer in an Observable, use its methods countObserversand deleteObserver.– Donat
Nov 15 '18 at 22:28
It depends on what you want to check. I assumed that the list is an object of some class that implements the interface
List. If does not depend on what is in the list. But be aware that the elements' equals() method. will be used to identifiy the element to be removed with list.remove. For the list of Observer in an Observable, use its methods countObserversand deleteObserver.– Donat
Nov 15 '18 at 22:28
Thank you for your help! I'm going to read read up on the methods you mentioned as they aren't ones I'm super familiar with at this point and I am eager to understand them more.
– Cassie
Nov 15 '18 at 23:02
Thank you for your help! I'm going to read read up on the methods you mentioned as they aren't ones I'm super familiar with at this point and I am eager to understand them more.
– Cassie
Nov 15 '18 at 23:02
add a comment |
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