Can someone explain me how to maintain data in array list during the running of app. Let say we have three classes. The main class run the app and the button "Save" add the data in the second class where is declared the private array list. Then when we added the data in array list , we click the button "Next scene". When is opened the second stage which is the third class, there is button "Show", that should show the data which were added in the first class, but it threw error that the array list is empty.
Code:
First class
public void start(Stage primaryStage) {
final Button btn = new Button();
btn.setLayoutX(121);
btn.setLayoutY(125);
btn.setText("Save");
btn.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent event) {
array.insert(20);
}
});
final Button btn_next = new Button();
btn_next.setLayoutX(btn.getLayoutY());
btn_next.setLayoutY(btn.getLayoutX() + 54);
btn_next.setText("Next Scene");
btn_next.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent event) {
secondStage.start();
}
});
Pane root = new Pane();
root.getChildren().add(btn);
root.getChildren().add(btn_next);
Scene scene = new Scene(root, 300, 250);
primaryStage.setTitle("Exercise");
primaryStage.setScene(scene);
primaryStage.show();
}
Second class
public class ArrayListClass {
private ArrayList <Integer> array = new ArrayList<>();
private ObservableList name_obs = FXCollections.observableArrayList(array);
public void insert(int maxBound) {
for(int i = 0; i < maxBound; i++) {
name_obs.add(i);
}
}
public Integer show(int i) {
return (Integer) name_obs.get(i);
}
}
Third class
public class SecondStage {
private Stage secondaryStage = new Stage();
ArrayListClass array = new ArrayListClass();
public void start() {
Button btn= new Button();
btn.setText("Show");
btn.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent event) {
System.out.println(array.show(5));
}
}
);
StackPane root = new StackPane();
root.getChildren().add(btn);
Scene scene = new Scene(root, 300, 250);
secondaryStage.setTitle("Exercise");
secondaryStage.setScene(scene);
secondaryStage.show();
}
}
ERROR:
Executing /Users/Jenda/NetBeansProjects/ExerciseArrayList/dist/run542796410/ExerciseArrayList.jar using platform /Library/Java/JavaVirtualMachines/jdk1.8.0_25.jdk/Contents/Home/jre/bin/java
Exception in thread "JavaFX Application Thread" java.lang.IndexOutOfBoundsException: Index: 5, Size: 0
at java.util.ArrayList.rangeCheck(ArrayList.java:653)
at java.util.ArrayList.get(ArrayList.java:429)
at com.sun.javafx.collections.ObservableListWrapper.get(ObservableListWrapper.java:89)
at exercisearraylist.ArrayListClass.show(ArrayListClass.java:36)
at exercisearraylist.SecondStage$1.handle(SecondStage.java:36)
at exercisearraylist.SecondStage$1.handle(SecondStage.java:31)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Node.fireEvent(Node.java:8216)
at javafx.scene.control.Button.fire(Button.java:185)
