Java 如何检查输入是否为整数？
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How to check if the input is an integer?
提问by Nikhil
I am taking input as integer using Scanner class. like this:in.nextInt();I need to prompt "wrong input" if user has entered any floating point number or character or string.
How can i accomplish this ?
我使用 Scanner 类将输入作为整数。像这样：in.nextInt();如果用户输入了任何浮点数或字符或字符串，我需要提示“错误输入”。我怎样才能做到这一点？
回答by Martijn Courteaux
Put it in a try-catch body.
把它放在一个 try-catch 主体中。
String input = scanner.next();
int inputInt 0;
try
{
inputInt = Integer.parseInt(input);
} catch (Exception e)
{
System.out.println("Wrong input");
System.exit(-1);
}
回答by Sotirios Delimanolis
nextInt()can only return an intif the InputStreamcontains an intas the next readable token.
nextInt()int如果InputStream包含 anint作为下一个可读标记，则只能返回 an 。
If you want to validate input, you should use something like nextLine()to read a full String, and use Integer.parseInt(thatString)to check if it is an integer.
如果你想验证输入，你应该使用类似nextLine()读取 full 的东西String，并使用Integer.parseInt(thatString)它来检查它是否是一个整数。
The method will throw a
该方法将抛出一个
NumberFormatException- if the string does not contain a parsable integer.
NumberFormatException- 如果字符串不包含可解析的整数。
回答by nasser-sh
As I mentioned in the comments, try using the try-catchstatement
正如我在评论中提到的，尝试使用try-catch语句
int someInteger;
try {
someInteger = Scanner.nextInt();
} catch (Exception e) {
System.out.println("The value you have input is not a valid integer");
}
