实施清除预填充字段/检查答案是否正确

Question

我想更改followmethod，以便没有预先填充LastName字段，并且如果输入的值等于theLastName字段，则它会检查私有布尔值isInputValid。此时，该字段始终是预填充的，它只是检查该字段是否为空。这两个变化的代码应该如何？

package ch.makery.address.view;

import javafx.fxml.FXML;
import javafx.scene.control.TextField;
import javafx.stage.Stage;

import org.controlsfx.dialog.Dialogs;

import ch.makery.address.model.Person;


/**
 * Dialog to train a word.
 * 
 * 
 */
public class EnglishTrainDialogController {

    @FXML
    private TextField firstNameField;
    @FXML
    private TextField lastNameField;
    @FXML



    private Stage dialogStage;
    private Person person;
    private boolean okClicked = false;

    /**
     * Initializes the controller class. This method is automatically called
     * after the fxml file has been loaded.
     */
    @FXML
    private void initialize() {
    }

    /**
     * Sets the stage of this dialog.
     * 
     * @param dialogStage
     */
    public void setDialogStage(Stage dialogStage) {
        this.dialogStage = dialogStage;
    }

    /**
     * Sets the person to be edited in the dialog.
     * 
     * @param person
     */
    public void setPerson(Person person) {
        this.person = person;

        firstNameField.setText(person.getFirstName());
        lastNameField.setText(person.getSecondEnglish());

    }

    /**
     * Returns true if the user clicked OK, false otherwise.
     * 
     * @return
     */
    public boolean isOkClicked() {
        return okClicked;
    }

    /**
     * Called when the user clicks Check and go back.
     */
    @FXML
    private void handleOk() {
        if (isInputValid()) {
            person.setFirstName(firstNameField.getText());
            person.setLastName(lastNameField.getText());


            okClicked = true;
            dialogStage.close();
        }
    }

    /**
     * Called when the user clicks cancel.
     */
    @FXML
    private void handleCancel() {
        dialogStage.close();
    }

    /**
     * Validates the user input in the text fields.
     * 
     * @return true if the input is valid
     */
    private boolean isInputValid() {
        String errorMessage = "";

        if (firstNameField.getText() == null || firstNameField.getText().length() == 0) {
            errorMessage += "No valid German word!\n"; 
        }
        if (lastNameField.getText() == null || lastNameField.getText().length() == 0) {
            errorMessage += "No valid English word!\n"; 
        }


        if (errorMessage.length() == 0) {
            return true;
        } else {
            // Show the error message.
            Dialogs.create()
                .title("wrong spelling")
                .masthead("Please correct!")
                .message(errorMessage)
                .showError();
            return false;
        }
    }
}