How to limit the amount of characters a javafx textfield - javafx

Question

I´m using a FXML to set my form, but I need to set the limit of characters in textfields. How can I made this ?

Answer 1

You can't directly set a limit to number of characters. But you can add a listener to lengthProperty() of the textfield
import javafx.application.Application;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.scene.Scene;
import javafx.scene.control.TextField;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
public class TextFieldLimit extends Application {
private static final int LIMIT = 10;
public static void main(String[] args) {
launch(args);
}
#Override
public void start(final Stage primaryStage) {
final TextField textField = new TextField();
textField.lengthProperty().addListener(new ChangeListener<Number>() {
#Override
public void changed(ObservableValue<? extends Number> observable,
Number oldValue, Number newValue) {
if (newValue.intValue() > oldValue.intValue()) {
// Check if the new character is greater than LIMIT
if (textField.getText().length() >= LIMIT) {
// if it's 11th character then just setText to previous
// one
textField.setText(textField.getText().substring(0, LIMIT));
}
}
}
});
VBox vbox = new VBox(20);
vbox.getChildren().add(textField);
Scene scene = new Scene(vbox, 400, 300);
primaryStage.setScene(scene);
primaryStage.show();
}
}

Answer 2

One more elegance solution
Pattern pattern = Pattern.compile(".{0,25}");
TextFormatter formatter = new TextFormatter((UnaryOperator<TextFormatter.Change>) change -> {
return pattern.matcher(change.getControlNewText()).matches() ? change : null;
});
textField.setTextFormatter(formatter);
where 0 and 25 - min and max amount of chars. + ability to set a pattern of input text

Answer 3

Here is my solution to limit the length of a textfield.
I would not recommend solutions which use a listener (on text property or on length property), they do not behave correctly in all situations (for what I have seen).
I create an HTML input text with a max length, and compare it to my textfield in JavaFX. I had the same behavior with paste operations (Ctrl + V), cancel operations (Ctrl + Z) in both cases. The goal here is to check if the text is valid BEFORE modifying the textfield.
We could use a similar approach for a numeric text field.
import java.util.Objects;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.scene.control.TextField;
public class LimitedTextField extends TextField {
private final IntegerProperty maxLength;
public LimitedTextField() {
super();
this.maxLength = new SimpleIntegerProperty(-1);
}
public IntegerProperty maxLengthProperty() {
return this.maxLength;
}
public final Integer getMaxLength() {
return this.maxLength.getValue();
}
public final void setMaxLength(Integer maxLength) {
Objects.requireNonNull(maxLength, "Max length cannot be null, -1 for no limit");
this.maxLength.setValue(maxLength);
}
#Override
public void replaceText(int start, int end, String insertedText) {
if (this.getMaxLength() <= 0) {
// Default behavior, in case of no max length
super.replaceText(start, end, insertedText);
}
else {
// Get the text in the textfield, before the user enters something
String currentText = this.getText() == null ? "" : this.getText();
// Compute the text that should normally be in the textfield now
String finalText = currentText.substring(0, start) + insertedText + currentText.substring(end);
// If the max length is not excedeed
int numberOfexceedingCharacters = finalText.length() - this.getMaxLength();
if (numberOfexceedingCharacters <= 0) {
// Normal behavior
super.replaceText(start, end, insertedText);
}
else {
// Otherwise, cut the the text that was going to be inserted
String cutInsertedText = insertedText.substring(
0,
insertedText.length() - numberOfexceedingCharacters
);
// And replace this text
super.replaceText(start, end, cutInsertedText);
}
}
}
}
Tested with JavaFX 8 and Java 8u45

Answer 4

This is a very simple solution that seems to work for me.
textfield.setOnKeyTyped(event ->{
int maxCharacters = 5;
if(tfInput.getText().length() > maxCharacters) event.consume();
});

Answer 5

I use a simple call to ChangeListener, where I test the condition to perform stops.
textFild.addListener((observable, oldValue, newValue) -> {
if (newValue.length() == MAX_SIZE) {
textField.setText(oldValue);
}
});

Answer 6

This is a better way to do the job on a generic text field:
public static void addTextLimiter(final TextField tf, final int maxLength) {
tf.textProperty().addListener(new ChangeListener<String>() {
#Override
public void changed(final ObservableValue<? extends String> ov, final String oldValue, final String newValue) {
if (tf.getText().length() > maxLength) {
String s = tf.getText().substring(0, maxLength);
tf.setText(s);
}
}
});
}
Works perfectly, except for that Undo bug.

Answer 7

the following 1-liner will exactly do it, wheras 5 is the limit of the TextField tf:
tf.setTextFormatter(new TextFormatter<>(c -> c.getControlNewText().matches(".{0,5}") ? c : null));

Answer 8

This is a solution that works well:
#FXML
void limitTextFields(KeyEvent event) {
int maxLength = 5;
TextField tf = (TextField) event.getSource();
if (tf.getText().length() > maxLength) {
tf.deletePreviousChar();
}
}