Data not getting displayed in Java FX Table when pressing button - javafx

Question

I am working with Table in Java FX. The code is below :
package addsubject;
import javafx.application.Application;
import static javafx.application.Application.launch;
import javafx.beans.property.SimpleStringProperty;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.TextField;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.control.cell.TextFieldTableCell;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.scene.text.Font;
import javafx.stage.Stage;
public class AddSubject extends Application {
private TableView<Subject> table = new TableView<Subject>();
private final ObservableList<Subject> data
= FXCollections.observableArrayList(new Subject("Mobile Computing", "5623"));
final HBox hb = new HBox();
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage stage) {
Scene scene = new Scene(new Group());
stage.setTitle("Add Subject");
stage.setWidth(700);
stage.setHeight(600);
final Label label = new Label("Subject Details");
label.setFont(new Font("Calibri", 20));
table.setEditable(true);
TableColumn sub = new TableColumn("Subject Name");
sub.setMinWidth(400);
sub.setCellValueFactory(
new PropertyValueFactory<Subject, String>("sub"));
sub.setCellFactory(TextFieldTableCell.forTableColumn());
sub.setOnEditCommit(
new EventHandler<TableColumn.CellEditEvent<Subject, String>>() {
#Override
public void handle(TableColumn.CellEditEvent<Subject, String> t) {
((Subject) t.getTableView().getItems().get(
t.getTablePosition().getRow())).setSubName(t.getNewValue());
}
}
);
TableColumn code = new TableColumn("Subject Code");
code.setMinWidth(150);
code.setCellValueFactory(
new PropertyValueFactory<Subject, String>("code"));
code.setCellFactory(TextFieldTableCell.forTableColumn());
code.setCellFactory(TextFieldTableCell.forTableColumn());
code.setOnEditCommit(
new EventHandler<TableColumn.CellEditEvent<Subject, String>>() {
#Override
public void handle(TableColumn.CellEditEvent<Subject, String> t) {
((Subject) t.getTableView().getItems().get(
t.getTablePosition().getRow())).setSubCode(t.getNewValue());
}
}
);
table.setItems(data);
table.getColumns().addAll(sub, code);
final TextField addSubName = new TextField();
addSubName.setPromptText("Subject Name");
addSubName.setPrefWidth(350);
final TextField addCode = new TextField();
addCode.setPrefWidth(150);
addCode.setPromptText("Subject Code");
final Button addButton = new Button("Add");
addButton.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent e) {
data.add(new Subject(
addSubName.getText(),
addCode.getText()));
addSubName.clear();
addCode.clear();
}
});
hb.getChildren().addAll(addSubName, addCode, addButton);
hb.setSpacing(5);
final VBox vbox = new VBox();
vbox.setSpacing(10);
vbox.setPadding(new Insets(10, 0, 0, 10));
vbox.getChildren().addAll(label, table, hb);
((Group) scene.getRoot()).getChildren().addAll(vbox);
stage.setScene(scene);
stage.show();
}
public static class Subject {
private final SimpleStringProperty sub;
private final SimpleStringProperty code;
private Subject(String subName, String subCode) {
this.sub = new SimpleStringProperty(subName);
this.code = new SimpleStringProperty(subCode);
}
public String getSubName() {
return sub.get();
}
public void setSubName(String subName) {
sub.set(subName);
}
public String getSubCode() {
return code.get();
}
public void setSubCode(String subCode) {
code.set(subCode);
}
}
}
I will say its working.
When I run the code, the Table should contain one row of information which is stored in 'data'. It is not displayed in the table when I run the code. How can I make it displayed ?
Next thing is to add new data to the Table when the 'Add' button is pressed after filling the 2 TextFields. I filled the 2 Text Fields, pressed the button and nothing appeared in the Table. How can I make it appear ?

Answer 1

The PropertyValueFactories are wrong. For example
new PropertyValueFactory<Subject, String>("sub")
This means your data object should have a method getSub() to return the value. But yours is
public String getSubName() {
return sub.get();
}
Either rename the Getter to getSub() or use new PropertyValueFactory<Subject, String>("subName")
The same applies to subject code.
You should read about JavaBeans naming conventions. Or this article on JavaFX Properties and Binding

Answer 2

Try implementing the following functions:
public StringProperty subProperty(){
return sub;
}
public StringProperty codeProperty(){
return code;
}
Why are these members final?