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Use byte multiplicative suffix size
Sandro Tosi, 28 January 2007
When you need to handle byte sizes as user input, could be easier, from a user point of view, to insert the value 650M instead of the exact value in bytes (681574400, for you information).
The Java method below does exactly this work: it tries to convert the input parameter in a number of bytes, even if it's using multiplicative suffix.Here is the code (highlighted with java2html), a wrapping (executable) class around it is available here:
/**
* Tries to convert size, expressed even with multiplicative
* suffix, into a number of bytes.
*
* For example, 120M will be come 125829120 (i.e. 120 x 1024 x
* 1024), and so on. If the parameter is a simple number
* (i.e. 512), no conversion is performed.
*
* Supported suffices are: 'k', 'K' (for KiloBytes), 'm', 'M' (for
* MegaBytes), 'g', 'G' (for GigaBytes).
*
* In case of any error during number conversion, a
* NumberFormatException is raised.
*
* @param sizeS string representing the size
* @return byte value of size passed as parameter
*/
public long byteSuffixSize(String sizeS) throws NumberFormatException {
long size = 0;
String quant = "";
char unit;
try {
// Try to convert the string to a long, since parameter
// could be a simple number
size = (new Integer(sizeS)).longValue();
} catch (NumberFormatException nfe) {
// it's a controlled situation; it could still be a
// multiplicative suffix
try {
// Take every char except the last
quant = sizeS.substring(0, sizeS.length()-1);
// Take the last char, maybe the multiplicative suffix
unit = sizeS.charAt(sizeS.length()-1);
size = (new Integer(quant)).longValue();
// Based on the suffix, evaluate the correct size
switch (unit){
case 'K':
case 'k':
size = size * 1024;
break;
case 'M':
case 'm':
size = size * 1024 * 1024;
break;
case 'G':
case 'g':
size = size * 1024 * 1024 * 1024;
break;
default:
// If it's not in previous cases, than it's not a
// multiplicative suffix, so die
throw new NumberFormatException();
}
} catch (Exception e) {
// In case of any error, die raising a
// NumberFormatException
throw new NumberFormatException(e.toString());
} // inner try..catch
} // outer try..catch
return size;
} // byteSuffixSize
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