如何在对话框输出中显示私有实例变量值[重复]

Question

此问题已经在这里有了答案：

How do getters and setters work?（6个答案）

关闭2分钟前。

我的程序遇到了一些困难。我试图在JOption窗格的对话框中输出一个私有实例变量。

公共类CarShowroom {

private String brand; 

private double horsepower; 

private String type; 

private int speed; 

private int engineSize; 


public CarShowroom (String model, String make, int power) {
    brand = model;

    type = make;

    speed = power;

}


public String getBrand() {
    return model;

}

public String getType() {
    return make;
}

public int getSpeed() {
    return power;
}

public void setEngineSize(int engineSize) {
    this.engineSize = engineSize;

}

public void setHorsepower(double horsepower) {
    this.horsepower = horsepower;

我在测试器类中创建了一个对象，该对象然后将值赋予setEngineSize（）方法。但是，当我然后尝试在带有字符串output1的对话框中输出此消息时，它不显示我为引擎或马力设置的值，我可能错过了什么？

import javax.swing.JOptionPane;

公共类CarShowroom {

static int input;
static boolean quit = false;

public static void main(String[] args) {

    CarShowroom Milan = new CarShowroom("Lamborghini", "Murciealago", 230);


    Milan.setEngineSize(4);
    Milan.setHorsepower(699.99);
    Milan.carSpecifications();


    do {
        String choice;
        int theNum;
        input = JOptionPane.showInputDialog("Good Ebening!" + "\n\n1. Show Car Specs
        \n\n2.Upgrade your car\n\n3.Quit the Program" + "\n\nPlease pick a one:");
        theNum = Integer.parseInt(choice);

        switch (theNum) {

        case 1:
            String option = Milan.getBrand();
            String option1 = Milan.getType();
            int option2 = Milan.getSpeed();

            int option4 = Milan.setEngineSize(4);
            double option5 = Milan.setHorsepower(699.99);


            String output1 = "The brand of your car is: " + option + "\nThe model of your Car is: " + option1 + "\nThe speed of your car is: " + option2 + "\nThe engine size of your car is: " +option4 + "\nThe horsepower of your car is: " +option5;

              JOptionPane.showConfirmDialog(null, output1, "Milan Showroom", JOptionPane.DEFAULT_OPTION);

              break;

        case 2:



        case 3:

            quit = true;

            break;


        }

    } while (!quit);
    JOptionPane.showMessageDialog(null,"You have left the showroom, come back!");

    }
}

Answer 1

在Carshowroom类上创建getter方法

int getEnginesize() {
  return this.enginesize;
}

double getHorsePower() {
  return this.horsepower;
}

并且在设置值之后，从getter方法获取值

Milan.setEngineSize(4);
Milan.setHorsepower(699.99);
int option4 = Milan.getEngineSize();
double option5 = Milan.getHorsePower();