如何使圆锥的体积和表面积保留2位小数呢

Question

package application;
    
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;


public class Main extends Application {
    TextField inputR=new TextField();
    TextField inputH=new TextField();
    TextField inputL=new TextField();
    TextField vol=new TextField();
    TextField sur=new TextField();
    Button calbtn=new Button("计算圆锥的体积和表面积");
        Button clearbtn=new Button("清空");
    
    
    @Override
    public void start(Stage primaryStage) {
        try {
            GridPane root = new GridPane();
            root.setPadding(new Insets(20,20,20,20));
            root.setHgap(20);
            root.setVgap(20);
            root.setStyle("-fx-background-color:lightblue");
            
            
            root.add(new Label("请输入圆锥的底面半径"), 0, 0);
            root.add(inputR, 1, 0);
            root.add(new Label("请输入圆锥的高"), 0, 1);
            root.add(inputH, 1, 1);
            root.add(new Label("请输入圆锥的母线长"), 0, 2);
            root.add(inputL, 1, 2);
            root.add(new Label("圆锥体积为"), 0, 4);
            root.add(vol, 1, 4);
            root.add(new Label("圆锥的表面积为"), 0, 3);
            root.add(sur, 1, 3);
            
            
            HBox hb=new HBox();
            hb.setSpacing(115);
            hb.getChildren().addAll(calbtn,clearbtn);
            hb.setAlignment(Pos.CENTER);
            root.add(hb, 0, 5,2,1);
        
            Police wang=new Police();
            calbtn.setOnAction(wang);
            
            clearbtn.setOnAction(wang);
            
            
            
            Scene scene = new Scene(root,400,400);
            scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
            primaryStage.setScene(scene);
            primaryStage.setTitle("求圆锥的表面积和体积");
        
            primaryStage.setResizable(false);
            
            primaryStage.show();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }
    
    public static void main(String[] args) {
        launch(args);
    }
    class Police implements EventHandler<ActionEvent>{

        @Override
        public void handle(ActionEvent arg0) {
            // TODO Auto-generated met


package application;
public class Cone9{
public double radius; public double height;public double line;
public Cone9(){}
public Cone9(double radius,double height, double line){
this.radius=radius; this.height=height;this.line=line;}

public double getSurface(){

return Math.PI*radius*radius+Math.PI*radius*line;}

public double getVolume(){
return Math.PI*radius*radius*height*(1/3d) ;}
}
![img](https://img-mid.csdnimg.cn/release/static/image/mid/ask/563108703456122.jpeg "#left")

Answer 1

Java 使用BigDecimal进行高精度加减乘除_西凉的悲伤的博客-CSDN博客_bigdecimal的加减乘除 有时候我们计算金钱或者其他一些计算的时候需要高精度的计算加减乘除，可以使用BigDecimal加：BigDecimal num1 = new BigDecimal("100.569");BigDecimal num2 = new BigDecimal("50.799");BigDecimal data = num1.add(num2);String result = String.valueOf(data);System.out.println(result);//输出151.368减： https://blog.csdn.net/qq_33697094/article/details/121530973