jodd.util.MathUtil Maven / Gradle / Ivy
// Copyright (c) 2003-present, Jodd Team (http://jodd.org)
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package jodd.util;
import java.util.concurrent.ThreadLocalRandom;
/**
* Various math utilities.
* note: Any random values from this class are not cryptographically secure!
*/
public class MathUtil {
/**
* Converts char digit into integer value.
* Accepts numeric chars (0 - 9) as well as letter (A-z).
*/
public static int parseDigit(final char digit) {
if ((digit >= '0') && (digit <= '9')) {
return digit - '0';
}
if (CharUtil.isLowercaseAlpha(digit)) {
return 10 + digit - 'a';
}
return 10 + digit - 'A';
}
/**
* Generates pseudo-random long from specific range. Generated number is
* great or equals to min parameter value and less then max parameter value.
*
* @param min lower (inclusive) boundary
* @param max higher (exclusive) boundary
*
* @return pseudo-random value
*/
public static long randomLong(final long min, final long max) {
return min + (long)(ThreadLocalRandom.current().nextDouble() * (max - min));
}
/**
* Generates pseudo-random integer from specific range. Generated number is
* great or equals to min parameter value and less then max parameter value.
*
* @param min lower (inclusive) boundary
* @param max higher (exclusive) boundary
*
* @return pseudo-random value
*/
public static int randomInt(final int min, final int max) {
return min + (int)(ThreadLocalRandom.current().nextDouble() * (max - min));
}
/**
* Returns true if a number is even.
*/
public static boolean isEven(final int x) {
return (x % 2) == 0;
}
/**
* Returns true if a number is odd.
*/
public static boolean isOdd(final int x) {
return (x % 2) != 0;
}
/**
* Formats byte size to human readable bytecount.
* https://stackoverflow.com/questions/3758606/how-to-convert-byte-size-into-human-readable-format-in-java/3758880#3758880
*/
public static String humanReadableByteCount(final long bytes, final boolean useSi) {
final int unit = useSi ? 1000 : 1024;
if (bytes < unit) {
return bytes + " B";
}
final int exp = (int) (Math.log(bytes) / Math.log(unit));
final String pre = (useSi ? "kMGTPE" : "KMGTPE").charAt(exp-1) + (useSi ? "" : "i");
return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
}
}