How to count the checkbox in flow pane (Java) - javafx

Question

#Override
public void initialize(URL url, ResourceBundle resourceBundle) {
System.out.println("confirmed");
this.refreshData( e -> true);
this.pieTriState.getData().forEach(this::clickOnPie);
Arrays.stream(gList).forEach(e -> {
var checkBox = new CheckBox(e.getState());
checkBox.setPrefSize(60,15);
this.fpStates.getChildren().add(checkBox);
System.out.println(checkBox);
checkBox.setOnAction((ActionEvent event) -> {
if(checkBox.isSelected()){
//I tried to count the checkbox by using this. but its not work for me
for(int i =0; i <1; i++){
System.out.println(i);
}
System.out.println(checkBox.getText());
//btnRefresh.setVisible(false);
//lblStatus.setText("more than 4 states selected is invalid.");
}
});
});
I am trying to count the checkbox. if 4 checkboxes are selected, so I can hide a button. But the problem is the checkbox is in the flow pane. So I don't know how to count it.

Answer 1

This answer uses the same concept (a filtered list) as this solution to:
Use a listener to get selected rows (mails) in tableView and add mails to my list of mails
but without a backing model or table.
The solution:
creates a list of checkboxes.
defines an extractor on the checkbox list so that a list change event occurs when the selection property of any checkbox in the list changes.
creates a filtered list of selected checkboxes based on the list of all checkboxes.
binds integer properties to the size of the two lists.
displays labels that represent the size properties as text counts of the number of elements in each list.
places the checkboxes in a FlowPane.
To understand the approach in more detail, read the text accompanying the linked solution.
import javafx.application.Application;
import javafx.beans.Observable;
import javafx.beans.binding.Bindings;
import javafx.beans.property.*;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.collections.transformation.FilteredList;
import javafx.geometry.Insets;
import javafx.geometry.Orientation;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.layout.*;
import javafx.stage.Stage;
public class CheckApp extends Application {
private static final int NUM_CHECKBOXES = 5;
#Override
public void start(Stage stage) {
// lists to track checkboxes and selected checkboxes.
ObservableList<CheckBox> checkBoxes = FXCollections.observableArrayList(
c -> new Observable[] { c.selectedProperty() }
);
FilteredList<CheckBox> selectedCheckBoxes = checkBoxes.filtered(
CheckBox::isSelected
);
// properties to track the size of the checkbox and selected checkbox lists.
IntegerProperty numCheckboxes = new SimpleIntegerProperty();
numCheckboxes.bind(Bindings.size(checkBoxes));
IntegerProperty numSelectedCheckboxes = new SimpleIntegerProperty();
numSelectedCheckboxes.bind(Bindings.size(selectedCheckBoxes));
// create the checkboxes.
for (int i = 0; i < NUM_CHECKBOXES; i++) {
checkBoxes.add(new CheckBox("" + (i+1)));
}
// create a flow pane to hold the checkboxes and put them inside.
FlowPane flowPane = new FlowPane(Orientation.VERTICAL, 10, 10);
flowPane.setPadding(new Insets(10));
flowPane.getChildren().addAll(checkBoxes);
// create text labels for the checkbox and selected checkbox counts.
Label numCheckboxesLabel = new Label();
numCheckboxesLabel.textProperty().bind(
numCheckboxes.asObject().asString()
);
Label numSelectedCheckboxesLabel = new Label();
numSelectedCheckboxesLabel.textProperty().bind(
numSelectedCheckboxes.asObject().asString()
);
// create some summary info
GridPane summaryInfo = new GridPane();
summaryInfo.setHgap(10);
summaryInfo.setVgap(5);
summaryInfo.addRow(0, new Label("# checkboxes:" ), numCheckboxesLabel);
summaryInfo.addRow(1, new Label("# selected checkboxes:" ), numSelectedCheckboxesLabel);
// layout the scene.
final VBox layout = new VBox(
10,
summaryInfo,
flowPane
);
layout.setPadding(new Insets(10));
layout.setPrefHeight(200);
stage.setScene(new Scene(layout));
stage.show();
}
}

Answer 2

Of the many ways, below is one of the approach you may give a try.
The idea is:
create a counter and create a boolean listener to increment the counter and check if it satisfies the condition
add this listener all the checkboxes selected property.
Outside the loop you need to include the below code:
IntegerProperty count = new SimpleIntegerProperty();
ChangeListener<Boolean> selectedListener = (obs,old,selected)->{
count.setValue(selected?count.get()+1:count.get()-1);
if(count.get()>=4){
// hide the button, set the error text
}else{
// unhide the button, clear the error text
}
};
And in the loop, after the checkbox is created , add the listener to checkbox:
checkBox.selectedProperty().addListener(selectedListener);