74. ListView and ObservableList

This program is similar to example 72, except now the ObservableList is connected to a ListView.

We break example 72 into 9 steps, and click on a button 9 times, and the ListView node updates. Clicking a 10th time will exit the program.

---

package ex74;

import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import java.util.Arrays;
import java.util.List;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ListView;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;
 
public class Ex74 extends Application {
    
    private final String style1 =
           "-fx-font-family: Georgia; -fx-font-size: 24;"
         + "-fx-text-fill: purple; -fx-background-color: greenyellow;";
    private final String style2 =
           "-fx-font-family: Georgia; -fx-font-size: 24;";
    
    ObservableList obsList;
    int step = 1;
    private Button button;
    
    
    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) throws Exception {
        
        button = new Button("Do step 1");
        appendButtonText(1);
        button.setPrefSize(200, 200);
        button.setStyle(style1);
        button.setWrapText(true);
        
        obsList = FXCollections.observableArrayList();
        
        ListView listView = new ListView<>(obsList);
        listView.setPrefSize(200, 400);
        listView.setStyle(style2);
        
        button.setOnAction( e -> {
            doStep(step);
            step++;
            if (step<10) {
                button.setText("Do step " + step);
                appendButtonText(step);
            }
            else button.setText("No more steps. Exit now!");
        });
        
        HBox hbox = new HBox(50, button, listView);
        hbox.setPadding(new Insets(20));
        
        Scene scene = new Scene(hbox);
        primaryStage.setTitle("Example 74. ListView and Observable List");
        primaryStage.setScene(scene);
        primaryStage.show();
    }
    
    private void doStep(int stepNumber) {
        switch (stepNumber) {
            case 1:
                List list = Arrays.asList("-1", "-2");
                obsList.addAll(list);
                break;
            case 2:
                obsList.addAll("1","2","3");
                break;
            case 3:
                obsList.add("4");
                break;
            case 4:
                obsList.add(0, "0");
                break;
            case 5:
                obsList.addAll("4", "5");
                break;
            case 6:
                obsList.set(1, "One");
                break;
            case 7:
                obsList.removeAll("3", "4");
                break;
            case 8:
                obsList.remove("1");
                break;
            case 9:
                obsList.clear();
                break;
            default:
                Platform.exit();
        }
    }
    
    private void appendButtonText(int stepNumber) {
        String val;
        switch (stepNumber) {
            case 1:
                val = " : Adding -1 and -2";
                break;
            case 2:
                val = " : Adding 1, 2, 3";
                break;
            case 3:
                val = " : Adding 4";
                break;
            case 4:
                val = " : Adding 0 at location 0";
                break;
            case 5:
                val = " : Adding 4 and 5";
                break;
            case 6:
                val = " : Changing location 1 to One";
                break;
            case 7:
                val = " : Removing 3 and 4";
                break;
            case 8:
                val = " : Removing 1";
                break;
            case 9:
                val = " : Clearing";
                break;
            default:
                val = " : Exit";
        }
        button.setText(button.getText() + val);
    }
}

---

This is the output after 5 steps and before Step 6 which will put One in location 1 (replacing -1):

---