vaadin-framework/documentation/articles/CreatingATextFieldForIntegerOnlyInputUsingADataSource.asciidoc

---
title: Creating A Text Field For Integer Only Input Using A Data Source
order: 30
layout: page
---

[[creating-a-textfield-for-integer-only-input-using-a-data-source]]
= Creating a TextField for integer only input using a data source

A `TextField` is a component that always has a value of type `String`. When
binding a property of another type to a text field, the value is
automatically converted if the conversion between the two types is
supported.

[source,java]
....
public class MyBean {
  private int value;

  public int getValue() {
    return value;
  }

  public void setValue(int integer) {
    value = integer;
  }
}
....

The property named "value" from a `BeanItem` constructed from `MyBean` will
be of type `Integer`. Binding the property to a `TextField` will
automatically make validation fail for texts that can not be converted
to an `Integer`.

[source,java]
....
final MyBean myBean = new MyBean();
BeanItem<MyBean> beanItem = new BeanItem<MyBean>(myBean);

final Property<Integer> integerProperty = (Property<Integer>) beanItem
    .getItemProperty("value");
final TextField textField = new TextField("Text field", integerProperty);

Button submitButton = new Button("Submit value", new ClickListener() {
  public void buttonClick(ClickEvent event) {
    String uiValue = textField.getValue();
    Integer propertyValue = integerProperty.getValue();
    int dataModelValue = myBean.getValue();

    Notification.show("UI value (String): " + uiValue
        + "\nProperty value (Integer): " + propertyValue
        + "\nData model value (int): " + dataModelValue);
   }
});

addComponent(new Label("Text field type: " + textField.getType()));
addComponent(new Label("Text field type: " + integerProperty.getType()));
addComponent(textField);
addComponent(submitButton);
....

With this example, entering a number and pressing the button causes the
value of the `TextField` to be a `String`, the property value will be an
`Integer` representing the same value and the value in the bean will be
the same int. If e.g. a letter is entered to the field and the button is
pressed, the validation will fail. This causes a notice to be displayed
for the field. The field value is still updated, but the property value
and the bean value are kept at their previous values.