java - 产品有效期(意外输出)

Question

问候!我编写了以下代码，预计可以处理该程序。如果用户手动给出的到期日期早于当前日期，则程序应终止，否则程序显示剩余期限。

当我输入到期日期作为当前日期时，即年:2014 年，月:3，日:7 按照我的预期，该计划应该已经终止，但它显示为 1 年等......剩余。我哪里做错了。

// Sets GregorianCalendar expiryDate object
static void setTrial(){
    System.out.println("\n----- SET TRIAL DATE ----\n");

    System.out.print("Year : ");
    int year = new Scanner(System.in).nextInt();

    System.out.print("Month : ");
    int month = new Scanner(System.in).nextInt();

    System.out.print("Day : ");
    int day = new Scanner(System.in).nextInt();

    expiryDate = new GregorianCalendar(year, month, day);
}

// Validates the expiryDate with current GregorianCalendar object
static void validate(){
    System.out.print("\n----- VALIDATING THE PRODUCT ----\n");
    GregorianCalendar current = new GregorianCalendar();

    if( current.after(expiryDate) ){        
        System.out.println("\nYour trial period is expired. Please buy the product.");
    }else{
        GregorianCalendar temp = new GregorianCalendar(expiryDate.get(GregorianCalendar.YEAR) - 
                        current.get(GregorianCalendar.YEAR), 
                        expiryDate.get(GregorianCalendar.MONTH) - 
                        current.get(GregorianCalendar.MONTH), 
                        expiryDate.get(GregorianCalendar.DAY_OF_MONTH) - 
                        current.get(GregorianCalendar.DAY_OF_MONTH));
        System.out.println("\nYou still have " + 
                        temp.get(GregorianCalendar.YEAR) + " years, " + 
                        temp.get(GregorianCalendar.MONTH) + " months, " + 
                        temp.get(GregorianCalendar.DAY_OF_MONTH) +
                        " days remaining... \n\nPlease buy the product before it expires!");
    }

Answer 1

月份从 0(一月)到 11(十二月)开始。

所以你需要这样做:

expiryDate = new GregorianCalendar(year, month-1, day);

另请注意，GregorianCalendar 没有 0 年(根据 definition Wikipedia gives )，这就是原因

System.out.println(new GregorianCalendar(0, 3, 8).get(GregorianCalendar.YEAR));

将打印 1。

相反，你可以这样做:

int yearsRemaining = expiryDate.get(GregorianCalendar.YEAR) - current.get(GregorianCalendar.YEAR);