java 扫描仪，使用分隔符
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Scanner, useDelimiter
提问by starcorn
I encounter some problem when using useDelimiter from the Scanner class.
使用 Scanner 类中的 useDelimiter 时遇到一些问题。
Scanner sc = new Scanner(System.in).useDelimiter("-");
while(sc.hasNext())
{
System.out.println(sc.next());
}
if I have this input
如果我有这个输入
A-B-C
美国广播公司
the output will be
输出将是
A B
AB
and wait until I type in another "-" for it to print out the last character
等到我输入另一个“-”，让它打印出最后一个字符
However if I instead of having user input data, and insert a String to the Scanner instead the code will work. What's the reason for it, and how do I fix it? I don't want to use StringTokenzier
但是，如果我没有让用户输入数据，而是向扫描仪插入一个字符串，则代码将起作用。它的原因是什么，我该如何解决？我不想使用 StringTokenzier
回答by jjnguy
If the Scannerdidn't wait for you to enter another -then it would erroneously assume that you were done typing input.
如果Scanner没有等待您输入另一个，-那么它会错误地认为您已完成输入。
What I mean is, the Scannermust wait for you to enter a -because it has no way to know the length of the next input.
我的意思是，Scanner必须等你输入a，-因为它无法知道下一个输入的长度。
So, if a user wanted to type A-B-CDEand you stopped to take a sip of coffee at C, it woud not get the correct input. (You expect [ A, B, CDE ]but it would get [ A, B, C ])
因此，如果用户想要输入A-B-CDE而您在 处停下C来喝一口咖啡，则不会得到正确的输入。（你期望[ A, B, CDE ]但它会得到[ A, B, C ]）
When you pass it in a full String, Scannerknows where the end of the input is, and doesn't need to wait for another delimiter.
当您以 full 形式传递它时String，Scanner知道输入的结尾在哪里，并且不需要等待另一个分隔符。
How I would do it follows:
我将如何做如下：
Scanner stdin = new Scanner(System.in);
String input = stdin.nextLine();
String[] splitInput = input.split("-", -1);
You will now have an array of Stringsthat contain the data between all of the -s.
您现在将拥有一个Strings包含所有-s之间数据的数组。
Here is a link to the String.split()documentation for your reading pleasure.
回答by stacker
You could use an alternative delimiter string useDelimiter( "-|\n" );It works with a String argument as well as by reading from System.in.
In case of System.in this requires you to press enter at the end of the line.
您可以使用替代分隔符字符串useDelimiter( "-|\n" );它适用于 String 参数以及从System.in. 在 System.in 的情况下，这需要您在行尾按 Enter。
回答by starcorn
How I would do it follows:
我将如何做如下：
Scanner stdin = new Scanner(System.in);
String s = stdin.nextLine();
String[] splitInput = s.split("-", -1);
You will now have an array of Stringsthat contain the data between all of the -s.
您现在将拥有一个Strings包含所有-s之间数据的数组。
