弹窗类

package cn.zxl.AlertWindow;

import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.VBox;
import javafx.stage.Modality;
import javafx.stage.Stage;

/**
 * @Description: //TODO 弹出窗口、消息对话框
 * @Author: zhangxueliang
 * @Create: 2021-05-27 09:50
 * @Version: 1.0
 **/
public class AlertWindow {
    private static boolean res;
    public static boolean display(String title,String msg){
        Stage stage = new Stage();
        stage.initModality(Modality.APPLICATION_MODAL);
        Label label = new Label();
        label.setText(msg);
        Button btn1 = new Button("是");
        Button btn2 = new Button("否");
        btn1.setOnMouseClicked(event -> {
            res=true;
            System.out.println("你点击了是");
            stage.close();
        });
        btn2.setOnMouseClicked(event -> {
            res=false;
            System.out.println("你点击了否");
            stage.close();
        });
        VBox vBox = new VBox();
        vBox.getChildren().addAll(label,btn1,btn2);
        //设置居中
        vBox.setAlignment(Pos.CENTER);
        Scene scene = new Scene(vBox,200,200);
        stage.setScene(scene);
        stage.setTitle(title);
        stage.showAndWait();

        return res;
    }
}

弹窗启动类

package cn.zxl.AlertWindow;

import javafx.application.Application;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

/**
 * @Description: //TODO 主类
 * @Author: zhangxueliang
 * @Create: 2021-05-27 09:50
 * @Version: 1.0
 **/
public class Main extends Application {
    @Override
    public void start(Stage primaryStage) throws Exception {
        Button btn = new Button("弹出窗口");
        btn.setOnMouseClicked(event -> {
            System.out.println(AlertWindow.display("新窗口", "是否关闭窗口"));
        });
        VBox vBox = new VBox();
        vBox.getChildren().add(btn);
        //设置居中显示
        vBox.setAlignment(Pos.CENTER);
        Scene scene = new Scene(vBox, 400, 400);
        primaryStage.setTitle("弹出窗口示例");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}

最终效果

单击弹出窗口按钮会弹出新窗口。

弹窗类

同上。

消息对话框启动类

package cn.zxl.AlertWindow;

import javafx.application.Application;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

/**
 * @Description: //TODO 消息提示框
 * @Author: zhangxueliang
 * @Create: 2021-05-27 09:50
 * @Version: 1.0
 **/
public class Main2 extends Application {
    Stage stage;
    @Override
    public void start(Stage primaryStage) throws Exception {
        stage = primaryStage;
        //单击系统自带的关闭按钮时也要弹出询问窗口
        stage.setOnCloseRequest(event -> {
            //点击了否,也会关闭窗口，所以要取消默认事件,单击否按钮不会关闭窗口
            event.consume();
            closeWindow();
        });
        Button btn = new Button("关闭窗口");
        btn.setOnMouseClicked(event -> closeWindow());
        VBox vBox = new VBox();
        vBox.getChildren().add(btn);
        //设置居中显示
        vBox.setAlignment(Pos.CENTER);
        Scene scene = new Scene(vBox, 400, 400);
        stage.setTitle("弹出窗口示例");
        stage.setScene(scene);
        stage.show();
    }
    /**
     * //TODO 如果点击了是按钮，就关闭所有窗口
     * @Description:  
     * @Create: 2021/5/27 10:59
     * @Author: zhangxueliang
     * @Param:
     * @Return: 
     */
    private void closeWindow() {
        boolean b = AlertWindow.display("新窗口", "是否关闭窗口");
        if (b) {
            stage.close();
        }
    }

    public static void main(String[] args) {
        launch(args);
    }
}

最终效果

单击是关闭窗口，单击否不关闭。
并且单击X按钮效果一样。