Can't stop javafx tables from ignoring my the setter function validation - validation

Question

I'm using javafx to do some table stuff. I want to validate my textfields in the myTextRow Class. In the "setText2" method I check the input if it is not bigger than 6 symbols, but it has no effects at all.
import java.util.ArrayList;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.scene.control.ContentDisplay;
import javafx.scene.control.TableCell;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TextArea;
import javafx.util.Callback;
import javafx.application.Application;
import static javafx.application.Application.launch;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;
public class Supermain extends Application {
#Override
public void start(Stage primaryStage) {
ArrayList myindizes=new ArrayList();
final TableView<myTextRow> table = new TableView<>();
table.setEditable(true);
table.setStyle("-fx-text-wrap: true;");
//Table columns
TableColumn<myTextRow, String> clmID = new TableColumn<>("ID");
clmID.setMinWidth(160);
clmID.setCellValueFactory(new PropertyValueFactory<>("ID"));
TableColumn<myTextRow, String> clmtext = new TableColumn<>("Text");
clmtext.setMinWidth(160);
clmtext.setCellValueFactory(new PropertyValueFactory<>("text"));
clmtext.setCellFactory(new TextFieldCellFactory());
TableColumn<myTextRow, String> clmtext2 = new TableColumn<>("Text2");
clmtext2.setMinWidth(160);
clmtext2.setCellValueFactory(new PropertyValueFactory<>("text2"));
clmtext2.setCellFactory(new TextFieldCellFactory());
//Add data
final ObservableList<myTextRow> data = FXCollections.observableArrayList(
new myTextRow(5, "Lorem","bla"),
new myTextRow(2, "Ipsum","bla")
);
table.getColumns().addAll(clmID, clmtext,clmtext2);
table.setItems(data);
HBox hBox = new HBox();
hBox.setSpacing(5.0);
hBox.setPadding(new Insets(5, 5, 5, 5));
Button btn = new Button();
btn.setText("Get Data");
btn.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent event) {
for (myTextRow data1 : data) {
System.out.println("data:" + data1.getText2());
}
}
});
hBox.getChildren().add(btn);
BorderPane pane = new BorderPane();
pane.setTop(hBox);
pane.setCenter(table);
primaryStage.setScene(new Scene(pane, 640, 480));
primaryStage.show();
}
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
launch(args);
}
public static class TextFieldCellFactory
implements Callback<TableColumn<myTextRow, String>, TableCell<myTextRow, String>> {
#Override
public TableCell<myTextRow, String> call(TableColumn<myTextRow, String> param) {
TextFieldCell textFieldCell = new TextFieldCell();
return textFieldCell;
}
public static class TextFieldCell extends TableCell<myTextRow, String> {
private TextArea textField;
private StringProperty boundToCurrently = null;
public TextFieldCell() {
textField = new TextArea();
textField.setWrapText(true);
textField.setMinWidth(this.getWidth() - this.getGraphicTextGap() * 2);
this.setGraphic(textField);
}
#Override
protected void updateItem(String item, boolean empty) {
super.updateItem(item, empty);
if (!empty) {
// Show the Text Field
this.setContentDisplay(ContentDisplay.GRAPHIC_ONLY);
// myindizes.add(getIndex());
// Retrieve the actual String Property that should be bound to the TextField
// If the TextField is currently bound to a different StringProperty
// Unbind the old property and rebind to the new one
ObservableValue<String> ov = getTableColumn().getCellObservableValue(getIndex());
SimpleStringProperty sp = (SimpleStringProperty) ov;
if (this.boundToCurrently == null) {
this.boundToCurrently = sp;
this.textField.textProperty().bindBidirectional(sp);
} else if (this.boundToCurrently != sp) {
this.textField.textProperty().unbindBidirectional(this.boundToCurrently);
this.boundToCurrently = sp;
this.textField.textProperty().bindBidirectional(this.boundToCurrently);
}
double height = real_lines_height(textField.getText(), this.getWidth(), 30, 22);
textField.setPrefHeight(height);
textField.setMaxHeight(height);
textField.setMaxHeight(Double.MAX_VALUE);
// if height bigger than the biggest height in the row
//-> change all heights of the row(textfields ()typeof textarea) to this height
// else leave the height as it is
//System.out.println("item=" + item + " ObservableValue<String>=" + ov.getValue());
//this.textField.setText(item); // No longer need this!!!
} else {
this.setContentDisplay(ContentDisplay.TEXT_ONLY);
}
}
}
}
public class myTextRow {
private final SimpleIntegerProperty ID;
private final SimpleStringProperty text;
private final SimpleStringProperty text2;
public myTextRow(int ID, String text,String text2) {
this.ID = new SimpleIntegerProperty(ID);
this.text = new SimpleStringProperty(text);
this.text2 = new SimpleStringProperty(text2);
}
public void setID(int id) {
this.ID.set(id);
}
public void setText(String text) {
this.text.set(text);
}
public void setText2(String text) {
if(text2check(text)){
this.text2.set(text);}
else
{System.out.println("wrong value!!!");}
}
public int getID() {
return ID.get();
}
public String getText() {
return text.get();
}
public StringProperty textProperty() {
return text;
}
public String getText2() {
return text2.get();
}
public StringProperty text2Property() {
return text2;
}
public IntegerProperty IDProperty() {
return ID;
}
public boolean text2check(String t)
{
if(t.length()>6)return false;
return true;
}
}
private static double real_lines_height(String s, double width, double heightCorrector, double widthCorrector) {
HBox h = new HBox();
Label l = new Label("Text");
h.getChildren().add(l);
Scene sc = new Scene(h);
l.applyCss();
double line_height = l.prefHeight(-1);
int new_lines = s.replaceAll("[^\r\n|\r|\n]", "").length();
// System.out.println("new lines= "+new_lines);
String[] lines = s.split("\r\n|\r|\n");
// System.out.println("line count func= "+ lines.length);
int count = 0;
//double rest=0;
for (int i = 0; i < lines.length; i++) {
double text_width = get_text_width(lines[i]);
double plus_lines = Math.ceil(text_width / (width - widthCorrector));
if (plus_lines > 1) {
count += plus_lines;
//rest+= (text_width / (width-widthCorrector)) - plus_lines;
} else {
count += 1;
}
}
//count+=(int) Math.ceil(rest);
count += new_lines - lines.length;
return count * line_height + heightCorrector;
}
private static double get_text_width(String s) {
HBox h = new HBox();
Label l = new Label(s);
l.setWrapText(false);
h.getChildren().add(l);
Scene sc = new Scene(h);
l.applyCss();
// System.out.println("dubbyloop.FXMLDocumentController.get_text_width(): "+l.prefWidth(-1));
return l.prefWidth(-1);
}
}

Answer 1

A rule of the JavaFX Properties pattern is that for a property x, invoking xProperty().setValue(value) should always be identical to invoking setX(value). Your validation makes this not true. The binding your cell implementation uses invokes the setValue method on the property, which is why it bypasses your validation check.
(Side note: in all the code I am going to change the names so that they adhere to proper naming conventions.)
The default way to implement a property in this pattern is:
public class MyTextRow {
private final StringProperty text = new SimpleStringProperty();
public StringProperty textProperty() {
return text ;
}
public final void setText(String text) {
textProperty().set(text);
}
public final String getText() {
return textProperty().get();
}
}
By having the set/get methods delegate to the appropriate property methods, you are guaranteed these rules are enforced, even if the textProperty() methods is overridden in a subclass. Making the set and get methods final ensures that the rule is not broken by a subclass overriding those methods.
One approach might be to override the set and setValue methods in the property, as follows:
public class MyTextRow {
private final StringProperty text2 = new StringPropertyBase() {
#Override
public String getName() {
return "text2";
}
#Override
public Object getBean() {
return MyTextRow.this ;
}
#Override
public void setValue(String value) {
if (text2Check(value)) {
super.setValue(value);
}
}
#Override
public void set(String value) {
if (text2Check(value)) {
super.set(value);
}
}
}
public StringProperty text2Property() {
return text2 ;
}
public final void setText2(String text2) {
text2Property().set(text2);
}
public final String getText2() {
return text2Property().get();
}
// ...
}
however, I think this will break the bidirectional binding that you have with the text property in the TextArea (basically, there is no way to communicate back to the text area when a change is vetoed, so the text area will not know to revert to the previous value). One fix would be to implement your cell using listeners on the properties instead of bindings. You could use a TextFormatter on the text area that simply updates the property and vetoes the text change if the change doesn't occur.
Here is a complete SSCCE using this approach:
import java.util.function.Function;
import java.util.function.UnaryOperator;
import javafx.application.Application;
import javafx.beans.property.Property;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import javafx.beans.property.StringPropertyBase;
import javafx.scene.Scene;
import javafx.scene.control.ContentDisplay;
import javafx.scene.control.TableCell;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.TextArea;
import javafx.scene.control.TextFormatter;
import javafx.scene.control.TextFormatter.Change;
import javafx.stage.Stage;
public class VetoStringChange extends Application {
#Override
public void start(Stage primaryStage) {
TableView<Item> table = new TableView<>();
table.setEditable(true);
table.getColumns().add(column("Item", Item::nameProperty));
table.getColumns().add(column("Description", Item::descriptionProperty));
for (int i = 1; i <= 20 ; i++) {
table.getItems().add(new Item("Item "+i, ""));
}
primaryStage.setScene(new Scene(table, 600, 600));
primaryStage.show();
}
public static <S> TableColumn<S,String> column(String title, Function<S,Property<String>> property) {
TableColumn<S,String> col = new TableColumn<>(title);
col.setCellValueFactory(cellData -> property.apply(cellData.getValue()));
col.setCellFactory(tc -> new TextAreaCell<S>(property));
col.setPrefWidth(200);
return col ;
}
public static class TextAreaCell<S> extends TableCell<S, String> {
private TextArea textArea ;
public TextAreaCell(Function<S, Property<String>> propertyAccessor) {
textArea = new TextArea();
textArea.setWrapText(true);
textArea.setMinWidth(this.getWidth() - this.getGraphicTextGap() * 2);
textArea.setMaxHeight(Double.MAX_VALUE);
UnaryOperator<Change> filter = c -> {
String proposedText = c.getControlNewText() ;
Property<String> prop = propertyAccessor.apply(getTableView().getItems().get(getIndex()));
prop.setValue(proposedText);
if (prop.getValue().equals(proposedText)) {
return c ;
} else {
return null ;
}
};
textArea.setTextFormatter(new TextFormatter<String>(filter));
this.setGraphic(textArea);
}
#Override
protected void updateItem(String item, boolean empty) {
super.updateItem(item, empty);
if (!empty) {
if (! textArea.getText().equals(item)) {
textArea.setText(item);
}
// Show the Text Field
this.setContentDisplay(ContentDisplay.GRAPHIC_ONLY);
} else {
this.setContentDisplay(ContentDisplay.TEXT_ONLY);
}
}
}
public static class Item {
private final StringProperty name = new StringPropertyBase() {
#Override
public Object getBean() {
return Item.this;
}
#Override
public String getName() {
return "name" ;
}
#Override
public void set(String value) {
if (checkValue(value)) {
super.set(value);
}
}
#Override
public void setValue(String value) {
if (checkValue(value)) {
super.setValue(value);
}
}
};
private final StringProperty description = new SimpleStringProperty();
public Item(String name, String description) {
setName(name);
setDescription(description);
}
private boolean checkValue(String value) {
return value.length() <= 6 ;
}
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 StringProperty descriptionProperty() {
return this.description;
}
public final String getDescription() {
return this.descriptionProperty().get();
}
public final void setDescription(final String description) {
this.descriptionProperty().set(description);
}
}
public static void main(String[] args) {
launch(args);
}
}
Another approach is to allow a "commit and revert" type strategy on your property:
public class MyTextRow {
private final StringProperty text2 = new SimpleStringProperty();
public MyTextRow() {
text2.addListener((obs, oldText, newText) -> {
if (! checkText2(newText)) {
// sanity check:
if (checkText2(oldText)) {
text2.set(oldText);
}
}
});
}
public StringProperty text2Property() {
return text ;
}
public final void setText2(String text2) {
text2Property().set(text2);
}
public final String getText2() {
return text2Property().get();
}
}
In general I dislike validation by listening for an invalid value and reverting like this, because other listeners to the property will see all the changes, including changes to and from invalid values. However, this might be the best option in this case.
Finally, you could consider vetoing invalid changes as in the first option, and also setting a TextFormatter on the control in the cell that simply doesn't allow text entry that results in an invalid string. This isn't always possible from a usability perspective (e.g. if empty strings are invalid, you almost always want to allow the user to temporarily delete all the text), and it means keeping two validation checks in sync in your code, which is a pain.