Module javafx.controls
Package javafx.scene.control.cell

Class CheckBoxListCell<T>

  • Type Parameters:
    T - The type of the elements contained within the ListView.
    All Implemented Interfaces:
    Styleable, EventTarget, Skinnable

    public class CheckBoxListCell<T>
extends ListCell<T>
    A class containing a ListCell implementation that draws a CheckBox node inside the cell, optionally with a label to indicate what the checkbox represents.

    The CheckBoxListCell is rendered with a CheckBox on the left-hand side of the ListView, and the text related to the list item taking up all remaining horizontal space.

    To construct an instance of this class, it is necessary to provide a Callback that, given an object of type T, will return a ObservableValue<Boolean> that represents whether the given item is selected or not. This ObservableValue will be bound bidirectionally (meaning that the CheckBox in the cell will set/unset this property based on user interactions, and the CheckBox will reflect the state of the ObservableValue<Boolean>, if it changes externally).

    Note that the CheckBoxListCell renders the CheckBox 'live', meaning that the CheckBox is always interactive and can be directly toggled by the user. This means that it is not necessary that the cell enter its editing state (usually by the user double-clicking on the cell). A side-effect of this is that the usual editing callbacks (such as on edit commit) will not be called. If you want to be notified of changes, it is recommended to directly observe the boolean properties that are manipulated by the CheckBox.

    Since:
    JavaFX 2.2
    See Also:
    CheckBox, ListCell

    • Constructor Detail

      • CheckBoxListCell

        public CheckBoxListCell​()
        Creates a default CheckBoxListCell.

      • CheckBoxListCell

        public CheckBoxListCell​(Callback<T,ObservableValue<Boolean>> getSelectedProperty)
        Creates a default CheckBoxListCell.
        Parameters:
        getSelectedProperty - A Callback that will return an ObservableValue<Boolean> given an item from the ListView.

      • CheckBoxListCell

        public CheckBoxListCell​(Callback<T,ObservableValue<Boolean>> getSelectedProperty,
                        StringConverter<T> converter)
        Creates a CheckBoxListCell with a custom string converter.
        Parameters:
        getSelectedProperty - A Callback that will return an ObservableValue<Boolean> given an item from the ListView.
        converter - A StringConverter that, given an object of type T, will return a String that can be used to represent the object visually.

    • Method Detail

      • forListView

        public static <T> Callback<ListView<T>,ListCell<T>> forListView​(Callback<T,ObservableValue<Boolean>> getSelectedProperty)
        Creates a cell factory for use in ListView controls. When used in a ListView, the CheckBoxListCell is rendered with a CheckBox on the left-hand side of the ListView, with the text related to the list item taking up all remaining horizontal space.
        Type Parameters:
        T - The type of the elements contained within the ListView.
        Parameters:
        getSelectedProperty - A Callback that, given an object of type T (which is a value taken out of the ListView<T>.items list), will return an ObservableValue<Boolean> that represents whether the given item is selected or not. This ObservableValue will be bound bidirectionally (meaning that the CheckBox in the cell will set/unset this property based on user interactions, and the CheckBox will reflect the state of the ObservableValue, if it changes externally).
        Returns:
        A Callback that will return a ListCell that is able to work on the type of element contained within the ListView items list.

      • forListView

        public static <T> Callback<ListView<T>,ListCell<T>> forListView​(Callback<T,ObservableValue<Boolean>> getSelectedProperty,
                                                                StringConverter<T> converter)
        Creates a cell factory for use in ListView controls. When used in a ListView, the CheckBoxListCell is rendered with a CheckBox on the left-hand side of the ListView, with the text related to the list item taking up all remaining horizontal space.
        Type Parameters:
        T - The type of the elements contained within the ListView.
        Parameters:
        getSelectedProperty - A Callback that, given an object of type T (which is a value taken out of the ListView<T>.items list), will return an ObservableValue<Boolean> that represents whether the given item is selected or not. This ObservableValue will be bound bidirectionally (meaning that the CheckBox in the cell will set/unset this property based on user interactions, and the CheckBox will reflect the state of the ObservableValue, if it changes externally).
        converter - A StringConverter that, give an object of type T, will return a String that can be used to represent the object visually.
        Returns:
        A Callback that will return a ListCell that is able to work on the type of element contained within the ListView.

      • getSelectedStateCallback

        public final Callback<T,ObservableValue<Boolean>> getSelectedStateCallback​()
        Returns the Callback that is bound to by the CheckBox shown on screen.
        Returns:
        the Callback that is bound to by the CheckBox shown on screen

      • updateItem

        public void updateItem​(T item,
                       boolean empty)
        The updateItem method should not be called by developers, but it is the best method for developers to override to allow for them to customise the visuals of the cell. To clarify, developers should never call this method in their code (they should leave it up to the UI control, such as the ListView control) to call this method. However, the purpose of having the updateItem method is so that developers, when specifying custom cell factories (again, like the ListView cell factory), the updateItem method can be overridden to allow for complete customisation of the cell.

        It is very important that subclasses of Cell override the updateItem method properly, as failure to do so will lead to issues such as blank cells or cells with unexpected content appearing within them. Here is an example of how to properly override the updateItem method: 

         protected void updateItem(T item, boolean empty) {
     super.updateItem(item, empty);

     if (empty || item == null) {
         setText(null);
         setGraphic(null);
     } else {
         setText(item.toString());
     }
 }

        Note in this code sample two important points:

        1. We call the super.updateItem(T, boolean) method. If this is not done, the item and empty properties are not correctly set, and you are likely to end up with graphical issues.
        2. We test for the empty condition, and if true, we set the text and graphic properties to null. If we do not do this, it is almost guaranteed that end users will see graphical artifacts in cells unexpectedly.
        Overrides:
        updateItem in class Cell<T>
        Parameters:
        item - The new item for the cell.
        empty - whether or not this cell represents data from the list. If it is empty, then it does not represent any domain data, but is a cell being used to render an "empty" row.