返回int时，int的“Java意外返回值”

Question

我让这个类在另一个文件中执行，java告诉我

"Unexpected return value", 

我搜索并搜索过，看不出我做错了什么。我是一个庞大的Java Noob，所以任何帮助都会受到赞赏。

import javafx.stage.*;
import javafx.scene.*;
import javafx.scene.layout.*;
import javafx.scene.control.*;
import javafx.geometry.*;

public class PopUpBox {

    public static void display(String title, String message) {
        Stage window = new Stage();
        TextField textField = new TextField();

        //Block events to other windows
        window.initModality(Modality.APPLICATION_MODAL);
        window.setTitle(title);
        window.setMinWidth(250);

        //Make a label that closes the window
        Label label = new Label();
        label.setText(message);
        Button closeButton = new Button("Done");
        closeButton.setOnAction(e -> {
                    Integer test = Integer.parseInt(textField.getText());
                    //return test;
                    System.out.println(test.getClass());
                    window.close();
                }
            );

        VBox layout = new VBox(10);
        layout.getChildren().addAll(textField, closeButton);
        layout.setAlignment(Pos.CENTER);

        //Display window and wait for it to be closed before returning
        Scene scene = new Scene(layout);
        window.setScene(scene);
        window.showAndWait();
    }

}