我编写了一个代码，该代码可以获取用户在开始日期和结束日期上的输入，并检查它们是否有效。在下面的代码中，我有2个do..while循环。一个用于开始日期，另一个用于结束日期。当执行第一个循环且不满足条件时，程序不会继续执行另一个do while循环。如果我可以收到解决此问题的方法，将会很有帮助。
int year, startMonth, endMonth, startDay, endDay;
boolean checkStartDate = false, checkEndDate = false;
Scanner input = new Scanner (System.in);
//checking Start Date
do
{
checkStartDate = false;
System.out.print("Enter the year: ");
year = input.nextInt();
System.out.print("Enter the start month: ");
startMonth = input.nextInt();
System.out.print("Enter the start day: ");
startDay = input.nextInt();
switch (startMonth)
{
case 1:
if(startDay <= 31)
{
checkStartDate = true;
}
break;
case 2:
if(startDay <= 28)
{
checkStartDate = true;
}
break;
case 3:
if(startDay <= 31)
{
checkStartDate = true;
}
break;
case 4:
if(startDay <= 30)
{
checkStartDate = true;
}
break;
case 5:
if(startDay <= 31)
{
checkStartDate = true;
}
break;
case 6:
if(startDay <= 30)
{
checkStartDate = true;
}
break;
case 7:
if(startDay <= 31)
{
checkStartDate = true;
}
break;
case 8:
if(startDay <= 31)
{
checkStartDate = true;
}
break;
case 9:
if(startDay <= 30)
{
checkStartDate = true;
}
break;
case 10:
if(startDay <= 31)
{
checkStartDate = true;
}
break;
case 11:
if(startDay <= 30)
{
checkStartDate = true;
}
break;
case 12:
if(startDay <= 31)
{
checkStartDate = true;
return;
}
default:
checkStartDate = false;
System.out.println("Try again and enter a valid date \n");
}
checkStartDate = false;
} while (checkStartDate = true);
//checking End Date
do
{
checkEndDate = false;
System.out.print("Enter the year: ");
year = input.nextInt();
System.out.print("Enter the start month: ");
endMonth = input.nextInt();
System.out.print("Enter the start day: ");
endDay = input.nextInt();
switch (endMonth)
{
case 1:
if(endDay <= 31)
{
checkEndDate = true;
}
else
{
checkEndDate = false;
System.out.println("Print a valid start day");
}
break;
case 2:
if(endDay <= 28)
{
checkEndDate = true;
}
break;
case 3:
if(endDay <= 31)
{
checkEndDate = true;
}
break;
case 4:
if(endDay <= 30)
{
checkEndDate = true;
}
break;
case 5:
if(endDay <= 31)
{
checkEndDate = true;
}
break;
case 6:
if(endDay <= 30)
{
checkEndDate = true;
}
break;
case 7:
if(endDay <= 31)
{
checkEndDate = true;
}
break;
case 8:
if(endDay <= 31)
{
checkEndDate = true;
}
break;
case 9:
if(endDay <= 30)
{
checkEndDate = true;
}
break;
case 10:
if(endDay <= 31)
{
checkEndDate = true;
}
break;
case 11:
if(endDay <= 30)
{
checkEndDate = true;
}
break;
case 12:
if(endDay <= 31)
{
checkEndDate = true;
return;
}
default:
checkEndDate = false;
System.out.println("Try again and enter a valid date \n");
}
checkEndDate = false;
} while (checkEndDate = true);
System.out.println("correct ");
答案 0 :(得分：2)
while (checkEndDate = true)
您正在分配 checkEndDate，因此循环将始终重复。您可能是说：
while (checkEndDate == true)
这比较两个值。但是，由于您已经有一个布尔值，因此不需要进行比较：
while (checkEndDate)
请注意，通过组合类似的案例，可以大大减少代码量。例如：
case 1:
case 3:
case 5:
case 7:
case 8:
case 10:
case 12:
if(startDay <= 31)
{
checkStartDate = true;
}
break;
30天的月份相同。
您还应该编写一个checkDate()方法，以免两次编写相同的代码。
答案 1 :(得分：0)
您在每个while循环的末尾添加了checkStartDate= false & checkEndDate = false;。这不是必需的。
使用布尔值将while条件更新为while (checkStartDate);。
下面是工作代码
int year，startMonth，endMonth，startDay，endDay; 布尔值checkStartDate = false，checkEndDate = false; 扫描仪输入=新的扫描仪（System.in）;
//checking Start Date
do
{
checkStartDate = false;
System.out.print("Enter the year: ");
year = input.nextInt();
System.out.print("Enter the start month: ");
startMonth = input.nextInt();
System.out.print("Enter the start day: ");
startDay = input.nextInt();
switch (startMonth)
{
case 1:
if(startDay <= 31)
{
checkStartDate = true;
}
break;
case 2:
if(startDay <= 28)
{
checkStartDate = true;
}
break;
case 3:
if(startDay <= 31)
{
checkStartDate = true;
}
break;
case 4:
if(startDay <= 30)
{
checkStartDate = true;
}
break;
case 5:
if(startDay <= 31)
{
checkStartDate = true;
}
break;
case 6:
if(startDay <= 30)
{
checkStartDate = true;
}
break;
case 7:
if(startDay <= 31)
{
checkStartDate = true;
}
break;
case 8:
if(startDay <= 31)
{
checkStartDate = true;
}
break;
case 9:
if(startDay <= 30)
{
checkStartDate = true;
}
break;
case 10:
if(startDay <= 31)
{
checkStartDate = true;
}
break;
case 11:
if(startDay <= 30)
{
checkStartDate = true;
}
break;
case 12:
if(startDay <= 31)
{
checkStartDate = true;
return;
}
default:
checkStartDate = false;
System.out.println("Try again and enter a valid date \n");
}
// checkStartDate = false;
} while (checkStartDate);
//checking End Date
do
{
checkEndDate = false;
System.out.print("Check End Date... ");
System.out.print("Enter the year: ");
year = input.nextInt();
System.out.print("Enter the start month: ");
endMonth = input.nextInt();
System.out.print("Enter the start day: ");
endDay = input.nextInt();
switch (endMonth)
{
case 1:
if(endDay <= 31)
{
checkEndDate = true;
}
else
{
checkEndDate = false;
System.out.println("Print a valid start day");
}
break;
case 2:
if(endDay <= 28)
{
checkEndDate = true;
}
break;
case 3:
if(endDay <= 31)
{
checkEndDate = true;
}
break;
case 4:
if(endDay <= 30)
{
checkEndDate = true;
}
break;
case 5:
if(endDay <= 31)
{
checkEndDate = true;
}
break;
case 6:
if(endDay <= 30)
{
checkEndDate = true;
}
break;
case 7:
if(endDay <= 31)
{
checkEndDate = true;
}
break;
case 8:
if(endDay <= 31)
{
checkEndDate = true;
}
break;
case 9:
if(endDay <= 30)
{
checkEndDate = true;
}
break;
case 10:
if(endDay <= 31)
{
checkEndDate = true;
}
break;
case 11:
if(endDay <= 30)
{
checkEndDate = true;
}
break;
case 12:
if(endDay <= 31)
{
checkEndDate = true;
return;
}
default:
checkEndDate = false;
System.out.println("Try again and enter a valid date \n");
}
// checkEndDate = false;
} while (checkEndDate);
System.out.println("correct ");