I have several TextFields that need to perform certain actions when focus is lost, like: trimming text, comparing it to initial one, checking it and if it's valid - saving. Which way would be better to handle it? By creating one ChangeListener with switch statement and sharing it among my Textfields:
ChangeListener<Boolean> focusHandler = new ChangeListener<Boolean>() {
private String initialValue = null;
@Override
public void changed(ObservableValue<? extends Boolean> observable, Boolean oldValue, Boolean focus) {
ReadOnlyBooleanProperty booleanProperty = (ReadOnlyBooleanProperty) observable;
TextField textField = (TextField)booleanProperty.getBean();
if (focus) { // gained focus
initialValue = textField.getText();
} else { // lost focus
trimText(textField);
if(!textField.getText().equals(initialValue)){ //text was changed
if(textField.getText().isEmpty()){ //text was erased
switch (textField.getId()) {
case CoreConstants.AREA_SIZE_TF:
emptyAreaSize();
break;
case CoreConstants.NUMBER_OF_PEOPLE_TF:
emptyPeopleLiving();
break;
default:
//no actions
break;
}
}else{
switch (textField.getId()) {
case CoreConstants.NAME_TF:
System.out.println("Execute name code!");
break;
case CoreConstants.SURNAME_TF:
System.out.println("Execute last name code!");
break;
case CoreConstants.MAIL_TF:
System.out.println("Execute mail code!");
break;
default:
//no actions
break;
}}}}}};
nameTextField.focusedProperty().addListener(focusHandler);
surnameTextField.focusedProperty().addListener(focusHandler);
Or by creating separate ChangeListener for each of TextFields like this:
numberOfPeopleTextField.focusedProperty().addListener(new ChangeListener<Boolean>() {
private String initialValue = null;
@Override
public void changed(ObservableValue<? extends Boolean> observable, Boolean oldValue, Boolean focus) {
if (focus) { // gained focus
initialValue = numberOfPeopleTextField.getText();
} else { // lost focus
trimText(numberOfPeopleTextField);
if(!numberOfPeopleTextField.getText().equals(initialValue)){ //text was changed
if(numberOfPeopleTextField.getText().isEmpty()){
emptyPeopleLiving();
}else{
mailInfoUpdate("mail");
}
}
}
}
});
mailTextField.focusedProperty().addListener(new ChangeListener<Boolean>() {
private String initialValue = null;
@Override
public void changed(ObservableValue<? extends Boolean> observable, Boolean oldValue, Boolean focus) {
if (focus) { // gained focus
initialValue = mailTextField.getText();
} else { // lost focus
trimText(mailTextField);
if(!mailTextField.getText().equals(initialValue)){ //text was changed
mailInfoUpdate("mail");
}
}
}
});
Creating several ChangeListeners VS one shared ChangeListener what is better to use and why?
I'd go with option 3: Create a class containing the common code and use different handlers.
class FocusChangeListener implements ChangeListener<Boolean> {
private final TextField textField;
private final Consumer<? super String> changeHandler;
private String initialValue = null;
FocusChangeListener(TextField textField, Consumer<? super String> changeHandler) {
this.textField = textField;
this.changeHandler = changeHandler;
}
@Override
public void changed(ObservableValue<? extends Boolean> observable, Boolean oldValue, Boolean focus) {
if (focus) { // gained focus
initialValue = textField.getText();
} else { // lost focus
trimText(textField);
if(changeHandler != null && !textField.getText().equals(initialValue)) { //text was changed
changeHandler.accept(textField.getText());
}
}
}
}
numberOfPeopleTextField.focusedProperty().addListener(new FocusChangeListener(numberOfPeopleTextField, text -> {
if(text.isEmpty()){
emptyPeopleLiving();
} else{
mailInfoUpdate("mail");
}
}));
mailTextField.focusedProperty().addListener(new FocusChangeListener(mailTextField, text -> mailInfoUpdate("mail")));
If it suits your needs better, you could also replace the Consumer with a abstract method in FocusChangeListener...
Switching on the id is a bad idea since it does not seperate the concerns in addition to using magic strings. Reimplementing the whole listener is not a good idea either since it makes the code harder to maintain...