JavaFX15.4 ( 创建一个簡单的计算器 ) 编写一个程序完成加法、减法、乘法和除法操作

package javaseniorprograme;

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.scene.text.Font;
import javafx.scene.text.Text;
import javafx.stage.Stage;

/**
 * 简易计算器
 * @author ASUS
 */
public class Exercise15_04 extends Application{
    private double d1,d2,d3;
    Double  c1,c2,c3,c4;
    String str1,str2;
    @Override
    public void start(Stage stage){
        HBox hbTop = new HBox();
        HBox hbBottom = new HBox();
        hbBottom.setAlignment(Pos.CENTER); 
        hbBottom.setSpacing(60); 
        VBox vbox = new VBox();
        vbox.setSpacing(15); 
        Text t1 = new Text("Number1:");
        t1.setFont(new Font(20)); 
        Text t2 = new Text("Number2:");
        t2.setFont(new Font(20)); 
        Text t3 = new Text("Result:");
        t3.setFont(new Font(20)); 
        TextField tf1 = new TextField();
        tf1.setEditable(true);
        TextField tf2 = new TextField();
        tf2.setEditable(true);
        TextField tf3 = new TextField();
        tf3.setEditable(true);
        
        hbTop.getChildren().addAll(t1,tf1,t2,tf2,t3,tf3);
        
        Button bt1 = new Button("Add");
        Button bt2 = new Button("Subtract");
        Button bt3 = new Button("Multiply");
        Button bt4 = new Button("Divide");
        hbBottom.getChildren().addAll(bt1,bt2,bt3,bt4);
        
        vbox.getChildren().addAll(hbTop,hbBottom);
        
        Scene scene = new Scene(vbox,500,80);
        stage.setTitle("Exercise15_04");
        stage.setScene(scene);
        stage.show();
        
        bt1.setOnAction((ActionEvent e) -> {
            str1 = tf1.getText();d1 = (double)Double.parseDouble(str1);
            str2 = tf2.getText();d2 = (double)Double.parseDouble(str2);
            d3 = d1+d2;
            c1 = new Double(d3);
            tf3.setText(c1.toString());
        }); 
        bt2.setOnAction((ActionEvent e) -> {
            str1 = tf1.getText();d1 = (double)Double.parseDouble(str1);
            str2 = tf2.getText();d2 = (double)Double.parseDouble(str2);
            d3 = d1-d2;
            c2 = new Double(d3);
            tf3.setText(c2.toString());
        });
        bt3.setOnAction((ActionEvent e) -> {
            str1 = tf1.getText();d1 = (double)Double.parseDouble(str1);
            str2 = tf2.getText();d2 = (double)Double.parseDouble(str2);
            d3 = d1*d2;
            c3 = new Double(d3);
            tf3.setText(c3.toString());
        });
        bt4.setOnAction((ActionEvent e) -> {
            str1 = tf1.getText();d1 = (double)Double.parseDouble(str1);
            str2 = tf2.getText();d2 = (double)Double.parseDouble(str2);
            d3 = d1/d2;
            c4 = new Double(d3);
            tf3.setText(c4.toString());
        });
    }
    public static void main(String[] args){
        Application.launch(args);
    } 
}