【发布时间】:2019-04-25 19:45:05
【问题描述】:
所以我有点困惑为什么会这样,这是我的代码:
public static void main (String[] args)
{
Scanner kb = new Scanner(System.in);
do
{
Scanner in = new Scanner(System.in);
System.out.println("Enter a time in 24-hour notation: ");
String time = in.nextLine();
int colonIndex = time.indexOf(":");
int hours = Integer.parseInt(time.substring(0, colonIndex));
int minutes = Integer.parseInt(time.substring(colonIndex + 1));
boolean legalTime = ((hours < 24 && hours > 0) && (minutes < 60 && minutes >= 0));
boolean addZero = minutes < 10;
boolean pm = hours > 12;
if(legalTime)
{
if(pm && addZero)
{
int newHour = hours - 12;
System.out.printf("That is the same as"
+ "\n%d:0%d PM\n", newHour, minutes);
}
else if(pm && !addZero)
{
hours = hours - 12;
System.out.printf("That is the same as"
+ "\n%d:%d PM\n", hours, minutes);
}
else if (!pm && addZero)
{
System.out.printf("That is the same as"
+ "\n%d:0%d AM\n", hours, minutes);
}
else
{
System.out.printf("That is the same as"
+ "\n%d:%d AM\n", hours, minutes);
}
}
try
{
if(!legalTime)
{
throw new Exception("Exception: there is no such time as " + time);
}
}
catch(Exception e)
{
System.out.println(e.getMessage()
+ "\nAgain? (y/n)");
continue;
}
System.out.println("Again? (y/n)");
}while(Character.toUpperCase(kb.next().charAt(0)) == 'Y');
}
我的代码本身不是问题,而是 do-while 循环的条件只能识别 do-while 之外的布尔值,在我看来,让条件受到内部任何内容的影响非常令人沮丧堵塞。我要做的是让我的代码运行,然后询问用户是否要再次运行它,用“y”或“n”表示。放不下
!time.charAt(0) == 'y'
作为条件,因为字符串“time”是在 do-while 循环内定义的,所以我做了一些奇怪的创可贴身体。我知道这很糟糕,但我想不出一种简单的方法来为这种不在 do-while 循环内的条件创建一个布尔值,我错过了什么吗?
【问题讨论】:
标签: java boolean java.util.scanner conditional-statements do-while