我必須從檔案中獲取一個數字，有些檔案包含字母和數字。喜歡 (dsh8kuebw9) 或有空格喜歡 (8 8) 我怎樣才能得到這些數字？我已經試過很多次了。我有一種方法來查找數字中出現的數字是 count8 方法。
parseInt 將檔案的行轉換為整數，但是因為在某些檔案中有字母我的方法有問題，因為它只接受整數而不接受字串
File file_a = new File("C:\\name\\textFile8a.txt");
try
{
FileReader in = new FileReader(file_a);
BufferedReader readFile = new BufferedReader(in);
String n = readFile.readLine();
int num = Integer.parseInt(n);
System.out.println(count8(num, 8));
}
catch(IOException e)
{
System.out.println("file could not be founded");
System.err.println("OIException: " e.getMessage());
}
uj5u.com熱心網友回復：
您可以在決議之前洗掉字串中的所有數字，方法是用空字串替換非數字字符：
String n = readFile.readLine();
n = n.replaceAll("[^0-9]", "");
int num = Integer.parseInt(n);
uj5u.com熱心網友回復：
基本和簡單的解決方案
public static ArrayList<Integer> extractNumber(String s) {
ArrayList returnList = new ArrayList<Integer>();
Pattern regex = Pattern.compile("\\d[\\d.]*");
Matcher matcher = regex.matcher(s);
while (matcher.find()) {
returnList.add(matcher.group());
}
return returnList;
}
public static void main(String[] args) {
File file_a = new File("C:\\name\\textFile8a.txt");
try {
FileReader in = new FileReader(file_a);
BufferedReader readFile = new BufferedReader(in);
String n = readFile.readLine();
ArrayList<Integer> numberList = extractNumber(n);
System.out.println(numberList);
} catch (IOException e) {
System.out.println("file could not be founded");
System.err.println("OIException: " e.getMessage());
}
}
uj5u.com熱心網友回復：
下面是一種方法，它將從提供的任意長度的輸入字串中提取任何有符號或無符號、整數或浮點數值，并在 String[] 陣列中回傳這些值。閱讀方法 JavaDoc 和方法中的注釋：
/**
* This method will extract all signed or unsigned Whole or floating point
* numbers from a supplied String. The numbers extracted are placed into a
* String[] array in the order of occurrence and returned.<br><br>
*
* It doesn't matter if the numbers within the supplied String have leading
* or trailing non-numerical (alpha) characters attached to them.<br><br>
*
* A Locale can also be optionally supplied so to use whatever decimal symbol
* that is desired otherwise, the decimal symbol for the system's current
* default locale is used.
*
* @param inputString (String) The supplied string to extract all the numbers
* from.<br>
*
* @param desiredLocale (Optional - Locale varArgs) If a locale is desired for a
* specific decimal symbol then that locale can be optionally
* supplied here. Only one Locale argument is expected and used
* if supplied.<br>
*
* @return (String[] Array) A String[] array is returned with each element of
* that array containing a number extracted from the supplied
* Input String in the order of occurrence. If the supplied Input
* String was found to be null or empty then a 0 length String[]
* Array is returned.
*/
public static String[] getNumbersFromString(String inputString, java.util.Locale... desiredLocale) {
if (inputString == null || inputString.isEmpty()) {
return new String[] {}; // Return a 0 length String Array.
}
// Get the decimal symbol the the current system's locale.
char decimalSeparator = new java.text.DecimalFormatSymbols().getDecimalSeparator();
/* Is there a supplied Locale? If so, set the decimal
separator to that for the supplied locale */
if (desiredLocale != null && desiredLocale.length > 0) {
decimalSeparator = new java.text.DecimalFormatSymbols(desiredLocale[0]).getDecimalSeparator();
}
/* The first replaceAll() removes all dashes (-) that are preceeded
or followed by whitespaces. The second replaceAll() removes all
periods from the input string except those that part of a floating
point number. The third replaceAll() removes everything else except
the actual numbers. */
return inputString.replaceAll("\\s*\\-\\s{1,}","")
.replaceAll("\\.(??)", "")
.replaceAll("[^-?\\d " decimalSeparator "\\d ]", " ")
.trim().split("\\s ");
}
如何使用此方法：
String filePath = "C:/name/textFile8a.txt";
String[] numbersArray = {};
// Get the decimal character used in the current System.
char decimalSeparator = new java.text.DecimalFormatSymbols().getDecimalSeparator();
// 'Try With Resources' used to to auto-close the reader and free resources.
try (java.io.BufferedReader reader = new java.io.BufferedReader(new java.io.FileReader(filePath))) {
String line;
int lineCounter = 0;
while ((line = reader.readLine()) != null) {
lineCounter ;
System.out.println("File Line #" lineCounter " contains:");
System.out.println("======================");
line = line.trim();
// Skip blank lines (if any).
if (line.isEmpty()) {
continue;
}
numbersArray = getNumbersFromString(line); // ****
/* Print the number(s) extracted from the file line
to the Console Window... */
for (String strgValue : numbersArray) {
// Do what you want with the numerical values, for example:
// Is this particular number a floating point value?
if (strgValue.contains(Character.toString(decimalSeparator))) {
// Yes it is...
double dblValue = Double.parseDouble(strgValue);
System.out.println("Extracted: -> " dblValue);
}
else {
//Nope..so it must be a Integer.
int intValue = Integer.parseInt(strgValue);
System.out.println("Extracted: -> " intValue);
}
// Or just print them all out...
// System.out.println(strgValue);
}
System.out.println();
}
}
catch (FileNotFoundException ex) {
System.out.println("File could not be found!");
}
catch (IOException ex) {
System.err.println("OIException: -> " ex.getMessage());
}
如果文本檔案包含：
This is the #1 line.
This is version2.45 of the 2nd line
abcd4256.4efgha67klmn-56.2opqr-12stuvw666.78.
777 535 55 88 999
-56.765
dsh8kuebw9
通過上面的代碼運行這個檔案，控制臺視窗將顯示：
File Line #1 contains:
======================
Extracted: -> 1
File Line #2 contains:
======================
Extracted: -> 2.45
Extracted: -> 2
File Line #3 contains:
======================
Extracted: -> 4256.4
Extracted: -> 67
Extracted: -> -56.2
Extracted: -> -12
Extracted: -> 666.78
File Line #4 contains:
======================
Extracted: -> 777
Extracted: -> 535
Extracted: -> 55
Extracted: -> 88
Extracted: -> 999
File Line #5 contains:
======================
Extracted: -> -56.765
File Line #6 contains:
======================
Extracted: -> 8
Extracted: -> 9
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