Java : Method return Issue

Question

您好，我创建了一个类来运行另一个测试类，但我遇到了一些问题。我已将agePremium 和ticketPremium 声明为私有(private) double 。后来我用两种方法分别计算保费。但是当它到达我不想在此处的另一个计算中使用计算变量的部分时

/* 
public double premium() {

    if (ticket <4){
        return ((BASE_PREMIUM*value) * agePremium) * ticketPremium;
    }
    else {
        System.out.println("Sorry, you have too many tickets !!");
        return 0;
    }
} 
*/  

它不会从我的方法中读取值，而是从声明和初始化中读取 1。

私有(private)双倍年龄溢价 =1;私有(private)双人票Premium =1;

它使它们相乘。

我如何让它们相互链接并用新值替换 1 并相乘。谢谢

import java.util.Scanner;

public class Driver {
    private int age;
    private int ticket;
    private double value;
    final double BASE_PREMIUM=0.05;
    private double agePremium =1;
    private double ticketPremium =1;


    Scanner scanner = new Scanner(System.in);

    public void read() {

        System.out.println("Driver’s Age?");
        age = scanner.nextInt();
        System.out.println("Number of Tickets?");
        ticket = scanner.nextInt();
        System.out.println("Value of Car?");
        value = scanner.nextDouble();
    }   

    public double premium() {

        if (ticket <4){
            return ((BASE_PREMIUM*value)*agePremium)*ticketPremium;
        }
        else {
            System.out.println("Sorry, you have too many tickets !!");
            return 0;
        }
    }   



    public void premiumAge() {
        if (age > 29) {
            agePremium += 0;
        }
        else if (age <= 29 && age >= 25) {
            agePremium += 0.10;
        }
        else {
            agePremium += 0.15;
        }
    }

    public void premiumTicket() {
        switch (ticket) {
        case '1':
            ticketPremium += 0.1;
            break;
        case '2':
            ticketPremium += 0.25;
            break;
        case '3':
            ticketPremium += 0.50;
            break;
        case '0':
            ticketPremium += 0.00;
        default:
            ticketPremium = 0.00;
            break;
        }
    }           
}

Answer 1

你的方法应该有点像这样，返回一个double以便访问另一个类中的私有(private)数据字段

public double premiumAge() {
    if ...
        return agePremium;
    else if ...
        return ....
    ...
}

如果您需要一个值，则需要返回一个值才能在另一个类中使用该方法。另外值得注意的是命名约定。当您希望方法访问私有(private)数据字段时，请使用带有 get 前缀的数据字段名称，例如。 agePremium : getAgePremium();

从另一个类访问

Driver driver = new Driver(); // create a Driver object (instantiate)
System.out.println(driver.premiumAge());

// Or if you follow the naming convention in your Driver class
System.out.println(driver.getAgePremium());