Removal of several identical elements ComboBox - javafx

Question

I have 4 ComboBox in each of them there are 5 elements: " ", "1", "2", "3", "4".
I have to make if the item "1" is selected in a ComboBox, it is automatically excluded from other .And if the item " " is selected in the ComboBoxinsame
it is automatically returned to the other. So same need for other items except " ".
I tried to do this Here's the code:
public void vubadditems(ComboBox<String> vub1,ComboBox<String> vub2,ComboBox<String> vub3,ComboBox<String> vub4){
vub1.getItems().addAll(" ","1","2","3","4");
vub2.getItems().addAll(" ","1","2","3","4");
vub3.getItems().addAll(" ","1","2","3","4");
vub4.getItems().addAll(" ","1","2","3","4");
}
public void vubact(ComboBox<String> vub1,ComboBox<String> vub2,ComboBox<String> vub3,ComboBox<String> vub4){
if(vub1.getSelectionModel().getSelectedItem()!=" "){
vub2.getItems().remove(vub1.getSelectionModel().getSelectedItem());
vub3.getItems().remove(vub1.getSelectionModel().getSelectedItem());
vub4.getItems().remove(vub1.getSelectionModel().getSelectedItem());
s=vub1.getSelectionModel().getSelectedItem();
}else{
}
if(vub2.getSelectionModel().getSelectedItem()!=" "){
vub1.getItems().remove(vub2.getSelectionModel().getSelectedItem());
vub3.getItems().remove(vub2.getSelectionModel().getSelectedItem());
vub4.getItems().remove(vub2.getSelectionModel().getSelectedItem());
}
if(vub3.getSelectionModel().getSelectedItem()!=" "){
vub1.getItems().remove(vub3.getSelectionModel().getSelectedItem());
vub2.getItems().remove(vub3.getSelectionModel().getSelectedItem());
vub4.getItems().remove(vub3.getSelectionModel().getSelectedItem());
}
if(vub4.getSelectionModel().getSelectedItem()!=" "){
vub1.getItems().remove(vub4.getSelectionModel().getSelectedItem());
vub2.getItems().remove(vub4.getSelectionModel().getSelectedItem());
vub3.getItems().remove(vub4.getSelectionModel().getSelectedItem());
}
}
public void vubq1ac(){
vubact(q1vub1,q1vub2,q1vub3,q1vub4);
}
public void initialize(){
vubadditems(q1vub1,q1vub2,q1vub3,q1vub4);
vubadditems(q2vub1,q2vub2,q2vub3,q2vub4);
vubadditems(q3vub1,q3vub2,q3vub3,q3vub4);
vubadditems(q4vub1,q4vub2,q4vub3,q4vub4);
vubadditems(q5vub1,q5vub2,q5vub3,q5vub4);
}
q1vub1, q1vub2, q1vub3, q1vub4 is loaded from FXML_file ComboBox's
I add vubq1ac as action listiner on ComboBox
But I have some Exception and program works incorrect
Exception:
Exception in thread "JavaFX Application Thread" java.lang.IndexOutOfBoundsException
at com.sun.javafx.scene.control.ReadOnlyUnbackedObservableList.subList(ReadOnlyUnbackedObservableList.java:136)
at javafx.collections.ListChangeListener$Change.getAddedSubList(ListChangeListener.java:242)
at com.sun.javafx.scene.control.behavior.ListViewBehavior.lambda$new$177(ListViewBehavior.java:269)
at javafx.collections.WeakListChangeListener.onChanged(WeakListChangeListener.java:88)
at com.sun.javafx.collections.ListListenerHelper$Generic.fireValueChangedEvent(ListListenerHelper.java:329)
at com.sun.javafx.collections.ListListenerHelper.fireValueChangedEvent(ListListenerHelper.java:73)
at com.sun.javafx.scene.control.ReadOnlyUnbackedObservableList.callObservers(ReadOnlyUnbackedObservableList.java:75)
at javafx.scene.control.MultipleSelectionModelBase.clearAndSelect(MultipleSelectionModelBase.java:378)
at javafx.scene.control.ListView$ListViewBitSetSelectionModel.clearAndSelect(ListView.java:1403)
at com.sun.javafx.scene.control.behavior.CellBehaviorBase.simpleSelect(CellBehaviorBase.java:256)
at com.sun.javafx.scene.control.behavior.CellBehaviorBase.doSelect(CellBehaviorBase.java:220)
at com.sun.javafx.scene.control.behavior.CellBehaviorBase.mousePressed(CellBehaviorBase.java:150)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:95)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:380)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:294)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:416)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:415)
at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
at com.sun.glass.ui.View.notifyMouse(View.java:937)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
at java.lang.Thread.run(Unknown Source)

Answer 1

If you follow your current approach your code will be quite long and rather hard to debug. Currently it seems that:
You only remove and never return items.
You don't store the previously selected value. Imagine that in your first ComboBox "1" was selected (and subsequently, excluded from other components), and you decide to change it back to " ". You can't get the previous value directly from the ComboBox, because .getSelectedItem() will only return the current value, which would be " " already.
I'll present you my approach and tell you briefly how it works.
public class JavaFXApplication extends Application {
public static void main(String[] args) {
Application.launch(args);
}
#Override
public void start(Stage primaryStage) {
FlowPane root = new FlowPane();
ArrayList<String> items = new ArrayList<>();
Collections.addAll(items, " ", "1", "2", "3", "4");
List<ComboBox> comboBoxList = new ArrayList<>();
for (int i = 0; i < 4; i++) {
ComboBox c = new ComboBox(FXCollections.observableArrayList(items));
c.setValue(c.getItems().get(0));
c.valueProperty().addListener(removeFromOtherCombo(comboBoxList, c));
comboBoxList.add(c);
}
root.getChildren().addAll(comboBoxList);
Scene scene = new Scene(root, 200, 100);
primaryStage.setScene(scene);
primaryStage.show();
}
public static ChangeListener removeFromOtherCombo(List<ComboBox> boxes, ComboBox current) {
return (o, oldVal, newVal) -> {
if (newVal.equals(oldVal)) {
return;
}
if (!oldVal.equals(" ")) {
boxes.stream()
.filter(c -> !c.equals(current))
.forEach((ComboBox) -> {
ComboBox.getItems().add(oldVal);
});
}
if (!newVal.equals(" ")) {
boxes.stream()
.filter(c -> !c.equals(current))
.forEach((ComboBox) -> {
ComboBox.getItems().remove(newVal);
});
}
};
}
}
For each ComboBox I create a ChangeListener that's aware of every other ComboBox and the ComboBox to which it's assigned.
c.valueProperty().addListener(removeFromOtherCombo(comboBoxList, c));
The ChangeListener is notified every time you pick a new value, and fortunately for us it receives both old and new value.
If old value is equal to new value then there's nothing for us to do.
if (newVal.equals(oldVal)) {
return;
}
If old value is a number (e.g. we're changing from "1" to "2") then we have to return the previously selected number to every ComboBox except one, which was filtered.
if (!oldVal.equals(" ")) {
boxes.stream()
.filter(c -> !c.equals(current))
.forEach((ComboBox) -> {
ComboBox.getItems().add(oldVal);
});
}
The same approach is taken when we're changing to a number, but this time we have to remove it from every ComboBox except one.