Question

Can anyone tell me whether there is an equivalent method in GWT like change in jQuery for form elements like radio-buttons, checkboxes, etc, which is fired the moment any such button is checked or unchecked? If so, how do I use it? I found a method like addValueChangeHandler in the Google docs, but apart from providing the prototype, there is no working example.

Specifically, if I want a handler which will wait for a checkbox being checked or unchecked, and accordingly pop up an alert like A checkbox has been checked!!, along with that buttons accompanying text.

Answer 1

CheckBox newOption = new CheckBox();
newOption.setText("Check to see alert");
newOption.addValueChangeHandler(new ValueChangeHandler<Boolean>() {

    @Override
    public void onValueChange(ValueChangeEvent<Boolean> event) {
        if (event.getValue()) {
            Window.alert("Checkbox is checked!");
        } else {
            Window.alert("Checkbox is unchecked!");
        }
    }

});