Example JavaFX ChoiceBox control backed by Database IDs

ChoiceBoxBackedByDatabaseIds.java

import javafx.application.Application;
import javafx.beans.value.*;
import javafx.collections.*;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class ChoiceBoxBackedByDatabaseIds extends Application {
  public static void main(String[] args) throws Exception { launch(args); }
  public void start(final Stage stage) throws Exception {
    // create a backing database;
    final Database db = new Database();

    // provide some instructions.
    final Label instructions = new Label("Choose an opponent.");
    instructions.setMouseTransparent(true);

    // provide some choices based on the animals in the database;
    ObservableList<Choice> choices = FXCollections.observableArrayList();
    choices.add(new Choice(null, "No selection"));
    for (Database.Animal animal : db.findAllAnimals()) {
      choices.add(new Choice(animal.id, animal.name));
    }
    final ChoiceBox<Choice> chooser = new ChoiceBox<>(choices);
    chooser.getSelectionModel().select(0);
    
    // act on a choice.
    chooser.getSelectionModel().selectedItemProperty().addListener(new ChangeListener<Choice>() {
      @Override public void changed(ObservableValue<? extends Choice> observableValue, Choice oldChoice, Choice newChoice) {
        if (newChoice.id == null) {
          instructions.setText("You have chosen cowardice.");
        } else {
          // lookup info by id in the database.
          Database.Animal opponent = db.findAnimal(newChoice.id);
          StringBuilder weapons = new StringBuilder();
          for (int weaponId : opponent.weaponIds) {
            weapons.append("\n ").append(db.findWeapon(weaponId).name);
          }

          // format and display the lookup info.
          instructions.setText(
            "You chosen to face the " + opponent.name + ".\n\n" +
            "Beware of your opponents deadly attacks:" + weapons + "\n\n" +
            "Good Luck!"
          );
        }
      }
    });

    // show the scene.
    final VBox layout = new VBox(20);
    layout.setStyle("-fx-background-color: cornsilk; -fx-padding: 10; -fx-font-size: 20;");
    layout.getChildren().addAll(instructions, chooser);
    Scene scene = new Scene(layout, 550, 350);
    stage.setScene(scene);
    stage.show();
  }

  /** Helper class for mapping a choice displayable in a ChoiceBox to a backing id. */
  class Choice {
    Integer id; String displayString;
    Choice(Integer id)                       { this(id, null); }
    Choice(String  displayString)            { this(null, displayString); }
    Choice(Integer id, String displayString) { this.id = id; this.displayString = displayString; }
    @Override public String toString() { return displayString; }
    @Override public boolean equals(Object o) {
      if (this == o) return true;
      if (o == null || getClass() != o.getClass()) return false;
      Choice choice = (Choice) o;
      return displayString != null && displayString.equals(choice.displayString) || id != null && id.equals(choice.id);
    }
    @Override public int hashCode() {
      int result = id != null ? id.hashCode() : 0;
      result = 31 * result + (displayString != null ? displayString.hashCode() : 0);
      return result;
    }
  }

  /** Quick and dirty in memory database */
  class Database {
    private Weapon[] weapons = {
      new Weapon(1, "Flaming Breath"), new Weapon(2, "Feathers of Doom"), new Weapon(3, "Sleeping Sickness"), new Weapon(4, "Drop from above"), new Weapon(5, "Laughter")
    };
    private Animal[] animals = {
      new Animal(1, "Burning Emu", 1, 2 ), new Animal(2, "Killer Koala", 3, 4), new Animal(3, "Outrageous Orangutan", 5)
    };
    
    Animal findAnimal(int id) { for (Animal animal : animals) if (animal.id == id) return animal; return null; }
    Animal[] findAllAnimals() { return animals; }
    Weapon findWeapon(int id) { for (Weapon weapon : weapons) if (weapon.id == id) return weapon; return null; }

    class Animal {
      int id; String name; int[] weaponIds;
      Animal(int id, String name, int... weaponIds) { this.id = id; this.name = name; this.weaponIds = weaponIds; }
      @Override public String toString() { return name; }
    }

    class Weapon {
      int id; String name;
      Weapon(int id, String name) { this.id = id; this.name = name; }
      @Override public String toString() { return name; }
    }
  }
}

https://forums.oracle.com/forums/thread.jspa?threadID=2316696&tstart=0

Great, Have you figured out to do the reverse, prompt choicebox from database: say i have Database A abc, B bcd and C cde with
choicebox {abc, bcd, cde}. If I want to prompt bcd
To use choice.getSelectionModel().select(1) where 1 is the index, I need the index for the id (A,B,C) , any idea how to get it.
Your Example:
chooser.getSelectionModel().select("Killer Koala");
or the ID
chooser.getSelectionModel().select(2); (that is ID 2 not index 2

I updated the gist to include an equivalence implementation for the Choice class so that you can perform selections using:
chooser.getSelectionModel().select(new Choice(2)) OR chooser.getSelectionModel().select(new Choice("Killer Koala"))

I added a comment to the linked forum thread to explain this in more detail.

Thanks so much, I struggled with this one!

Saved me a lot of work with such a simple concept. Thanks!

Thank you!