共享 ChangeListener VS 多个 ChangeListeners？

Question

我有几个 TextField 需要在失去焦点时执行某些操作，例如：修剪文本，将其与初始文本进行比较，检查它以及它是否有效 - 保存。哪种方式处理比较好？通过使用 switch 语句创建一个 ChangeListener 并在我的 Textfield 中共享它：

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);

或者像这样为每个 TextField 创建单独的 ChangeListener：

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");
            }
        }
    }
});

创建多个 ChangeListener VS 一个共享 ChangeListener 哪个更好用，为什么？

Answer 1

我会选择选项 3：创建一个 class 包含通用代码并使用不同的处理程序。

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")));

如果更符合您的需求，您也可以将 Consumer 替换为 FocusChangeListener 中的抽象方法...

打开 id 是个坏主意，因为除了使用魔术字符串外，它不会分离问题。重新实现整个监听器也不是一个好主意，因为它会使代码更难维护...

共享 ChangeListener VS 多个 ChangeListeners？

Shared ChangeListener VS multiple ChangeListeners?

javafx

event-handling

changelistener