sc = new Scanner(new File(dataFile));
sc.useDelimiter(",|\r\n");
我不明白分隔符是如何工作的,有人可以用外行术语解释一下吗?
扫描仪还可以使用空格以外的分隔符。
简单的例子来自扫描仪API https://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html:
String input = "1 fish 2 fish red fish blue fish";
// \\s* means 0 or more repetitions of any whitespace character
// fish is the pattern to find
Scanner s = new Scanner(input).useDelimiter("\\s*fish\\s*");
System.out.println(s.nextInt()); // prints: 1
System.out.println(s.nextInt()); // prints: 2
System.out.println(s.next()); // prints: red
System.out.println(s.next()); // prints: blue
// don't forget to close the scanner!!
s.close();
重点是理解正则表达式(regex https://en.wikipedia.org/wiki/Regular_expression) 在 - 的里面Scanner::useDelimiter https://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html#useDelimiter(java.util.regex.Pattern)。找到一个useDelimiter
教程here http://javatutorialhq.com/java/util/scanner-class-tutorial/usedelimiter-string-pattern-method-example/.
从正则表达式开始在这里你可以找到 http://regexone.com/一个很好的教程。
Notes
abc… Letters
123… Digits
\d Any Digit
\D Any Non-digit character
. Any Character
\. Period
[abc] Only a, b, or c
[^abc] Not a, b, nor c
[a-z] Characters a to z
[0-9] Numbers 0 to 9
\w Any Alphanumeric character
\W Any Non-alphanumeric character
{m} m Repetitions
{m,n} m to n Repetitions
* Zero or more repetitions
+ One or more repetitions
? Optional character
\s Any Whitespace
\S Any Non-whitespace character
^…$ Starts and ends
(…) Capture Group
(a(bc)) Capture Sub-group
(.*) Capture all
(ab|cd) Matches ab or cd
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