JavaFX FilteredList filtering based on property of items in a list

Question

I have a case where I need to filter out an ObservableList<Item> based on some properties of the elements (i.e. the condition is internal, not external). I found out that javafx has a FilteredList , so I tried. I could set the predicate and filtering until the property value that defines the filtering changes. The predicate is now configured as follows:

 list.setPredicate(t -> !t.filteredProperty().get()) 

Since the predicate returns boolean, not BooleanProperty, changes to this property are not reflected in the list.

Is there an easy solution to this? I could try to do some workarounds, for example. create a separate list and synchronize this, or reset the predicate every time the property changes in one element, hoping to restart the filtering, but first I wanted to ask if someone knows a pretty acceptable solution, since these workarounds are certainly not.

Answer 1

Create a basic list using an extractor . This will allow the base list to trigger update events when filteredProperty() changes for any items. FilteredList will monitor these events and therefore will be updated accordingly:

 ObservableList<Item> baseList = FXCollections.observableArrayList(item -> new Observable[] {item.filteredProperty()}); FilteredList<Item> list = new FilteredList<>(baseList, t -> ! t.filteredProperty().get()); 

Quick demo:

 import java.util.stream.IntStream; import javafx.beans.Observable; import javafx.beans.property.BooleanProperty; import javafx.beans.property.SimpleBooleanProperty; import javafx.beans.property.SimpleStringProperty; import javafx.beans.property.StringProperty; import javafx.collections.FXCollections; import javafx.collections.ListChangeListener.Change; import javafx.collections.ObservableList; import javafx.collections.transformation.FilteredList; public class DynamicFilteredListTest { public static void main(String[] args) { ObservableList<Item> baseList = FXCollections.observableArrayList(item -> new Observable[] {item.filteredProperty()}); FilteredList<Item> list = new FilteredList<>(baseList, t -> ! t.isFiltered()); list.addListener((Change<? extends Item> c) -> { while (c.next()) { if (c.wasAdded()) { System.out.println(c.getAddedSubList()+ " added to filtered list"); } if (c.wasRemoved()) { System.out.println(c.getRemoved()+ " removed from filtered list"); } } }); System.out.println("Adding ten items to base list:\n"); IntStream.rangeClosed(1, 10).mapToObj(i -> new Item("Item "+i)).forEach(baseList::add); System.out.println("\nFiltered list now:\n"+list); System.out.println("\nSetting filtered flag for alternate items in base list:\n"); IntStream.range(0, 5).map(i -> 2*i).mapToObj(baseList::get).forEach(i -> i.setFiltered(true)); System.out.println("\nFiltered list now:\n"+list); } public static class Item { private final StringProperty name = new SimpleStringProperty() ; private final BooleanProperty filtered = new SimpleBooleanProperty() ; public Item(String name) { setName(name); } public final StringProperty nameProperty() { return this.name; } public final String getName() { return this.nameProperty().get(); } public final void setName(final String name) { this.nameProperty().set(name); } public final BooleanProperty filteredProperty() { return this.filtered; } public final boolean isFiltered() { return this.filteredProperty().get(); } public final void setFiltered(final boolean filtered) { this.filteredProperty().set(filtered); } @Override public String toString() { return getName(); } } } 

Answer 2

If you use the database load function and you need to filter multiple fields, this solution will help.

  ObservableList<PurchaseOrder> poData = FXCollections.observableArrayList(); FilteredList<PurchaseOrder> filteredData; private void load() { PurchaseOrder po = new PurchaseOrder(); try { poData = po.loadTable("purchase_orders", beanFields); // Database loading data } catch (SQLException ex) { Logger.getLogger(PurchaseOrdersController.class.getName()).log(Level.SEVERE, null, ex); } filteredData = new FilteredList<>(poData, t -> true); //Encapsulate data with filter poTable.setItems(filteredData); //Load filtered data into table //Set event trigger for all filter textboxes txtFilter.textProperty().addListener(obs->{ filter(filteredData); }); txtFilter2.textProperty().addListener(obs->{ filter(filteredData); }); } private void filter(FilteredList<PurchaseOrder> filteredData) { filteredData.setPredicate(PurchaseOrder -> { // If all filters are empty then display all Purchase Orders if ((txtFilter.getText() == null || txtFilter.getText().isEmpty()) && (txtFilter2.getText() == null || txtFilter2.getText().isEmpty())) { return true; } // Convert filters to lower case String lowerCaseFilter = txtFilter.getText().toLowerCase(); String lowerCaseFilter2 = txtFilter2.getText().toLowerCase(); //If fails any given criteria, fail completely if(txtFilter.getText().length()>0) if (PurchaseOrder.get("vendor_name").toLowerCase().contains(lowerCaseFilter) == false) return false; if(txtFilter2.getText().length()>0) if (PurchaseOrder.get("PONumber").toLowerCase().contains(lowerCaseFilter2) == false) return false; return true; // Matches given criteria }); }