Java：输入无效数据时重新提示用户输入的更简单方法
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Java: Easier Way to Re-prompt user for input when invalid data is entered
提问by Singh
I am creating a simple program using the java language which uses a bunch of similar methods to retrieve information from the user. The method i have used to deal with the user entering invalid data seems very incorrect to me, so i am seeking professional guidance on how to better handle invalid data.
我正在使用 java 语言创建一个简单的程序，该程序使用一堆类似的方法从用户那里检索信息。我用来处理用户输入无效数据的方法对我来说似乎很不正确，所以我正在寻求有关如何更好地处理无效数据的专业指导。
I have attempted to search for similar questions but have found none.
我试图搜索类似的问题，但没有找到。
This is a sample of one of my methods:
这是我的一种方法的示例：
public static int getInput()
{
int temp = 1;
do
{
System.out.println("Answers must be between 1 and 15");
temp = reader.nextInt();
if(temp >=1 && temp <= 15)
{
return temp;
}
else
{
System.out.println("Please enter a valid value");
}
}while(temp > 15 || temp < 1);
//This value will never be reached because the do while loop structure will not end until a valid return value is determined
return 1;
}//End of getInput method
Is there a better way to write this method?
有没有更好的方法来编写这个方法？
This question is entirely made up so i can learn a better method to implement in my future programs.
这个问题是完全弥补的，所以我可以学习一种更好的方法来在我未来的程序中实现。
Is using a labeled break statement acceptable? such as:
使用带标签的 break 语句是否可以接受？如：
public static int getInput()
{
int temp = 1;
start:
System.out.println("Answers must be between 1 and 15");
temp = reader.nextInt();
if(temp >=1 && temp <= 15)
{
return temp;
}
else
{
System.out.println("Please enter a valid value");
break start;
}
}
Thank you very much in advance.
非常感谢您提前。
回答by qqilihq
You have forgotten to check the case, that non-number values are entered (Scanner#nextIntthrows a java.util.InputMismatchException). One suggestion which takes care of that issue, is less redundant and more flexible:
您忘记检查大小写，输入了非数字值（Scanner#nextInt抛出 a java.util.InputMismatchException）。解决这个问题的一个建议是不那么多余且更灵活：
public static int getInput(int min, int max) {
for (;;) {
Scanner scanner = new Scanner(System.in);
System.out.println(String.format("Answers must be between %s and %s", min, max));
try {
int value = scanner.nextInt();
if (min <= value && value <= max) {
return value;
} else {
System.out.println("Please enter a valid value");
}
} catch (InputMismatchException e) {
System.out.println("Input was no number");
}
}
}
回答by Dan675
If you are just worried about the return that is not used and double checking temp you can do something like
如果您只是担心未使用的退货并仔细检查温度，您可以执行以下操作
public static int getInput()
{
while(true)
{
System.out.println("Answers must be between 1 and 15");
temp = reader.nextInt();
if(temp >=1 && temp <= 15)
{
return temp;
}
else
{
System.out.println("Please enter a valid value");
}
}
}//End of getInput method
