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Multiples of bytes

Multiples of bytes
SI decimal prefixes		IEC binary prefixes
Name (Symbol)	Value	Name (Symbol)	Value
kilobyte (kB)	103	kibibyte (KiB)	210 = 1.024 × 103
megabyte (MB)	106	mebibyte (MiB)	220 ≈ 1.049 × 106
gigabyte (GB)	109	gibibyte (GiB)	230 ≈ 1.074 × 109
terabyte (TB)	1012	tebibyte (TiB)	240 ≈ 1.100 × 1012
petabyte (PB)	1015	pebibyte (PiB)	250 ≈ 1.126 × 1015
exabyte (EB)	1018	exbibyte (EiB)	260 ≈ 1.153 × 1018
zettabyte (ZB)	1021	zebibyte (ZiB)	270 ≈ 1.181 × 1021
yottabyte (YB)	1024	yobibyte (YiB)	280 ≈ 1.209 × 1024

Convert byte size into human readable format in Java ( and GWT )

Java:

public static String humanReadableByteCount(long bytes, boolean si) {
    int unit = si ? 1000 : 1024;
    if (bytes < unit) return bytes + " B";
    int exp = (int) (Math.log(bytes) / Math.log(unit));
    String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp-1) + (si ? "" : "i");
    return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
}

Java GWT:

public static String humanReadableByteCount(long bytes, boolean si) {
 int unit = si ? 1000 : 1024;
 if (bytes < unit)
  return bytes + " B";
 int exp = (int) (Math.log(bytes) / Math.log(unit));
 String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1)
   + (si ? "" : "i");
 return toFixed(bytes / Math.pow(unit, exp), 1) + " " + pre
    + "B";
}
public static native String toFixed(double d, int fixed)/*-{
  return d.toFixed(fixed);
}-*/;

Orgin from here

JSNI function in GWT to format numbers

public class NumberUtil {
 
 public static native String toFixed(double d, int fixed)/*-{
  return d.toFixed(fixed);
 }-*/;
 
 public static native String toPrecision(double d, int precision)/*-{
  return d.toPrecision(precision);
 }-*/;

}

see also this article.

Format numbers in javascript

var num = 1;
var result = num.toFixed(2); // result = 1.00

num = 123.4567;
result = num.toFixed(3); // result = 123.456

num = 123.4567;
result = num.toPrecision(4); // result = 123.4

num = 123.4567;
result = num.toPrecision(3); // result = 123

num = 555.55;
result = num.toPrecision(2); // result will equal 5.6e+2

see also this article.

DATE and TIME in TCL script using clock

TCL: clock command

GWT: JSNI function to validate URL

public native boolean isValidUrl(String url) /*-{
    var pattern = /(http|https):\/\/(\w+:{0,1}\w*@)?(\S+)(:[0-9]+)?(\/|\/([\w#!:.?+=&%@!\-\/]))?/;
    return pattern.test(url);
}-*/;

Java: use signed types to store unsigned values

short, int, long are always signed in Java. However, it only matters if you are doing math with it. Otherwise, you can store unsigned values using the signed types by utilizing the sign bit.

If you do need to do some math:

1) for unsigned short, us,

convert it to int by masking: int i = us & 0xffff;

Do all arithmetic with int operands, modulo 0xffff.

When you are done, cast the result back to int and transmit it.

2) for unsigned int, ui,

convert it to long by masking: long l = ui & 0xffffffffL;

Do all arithmetic with long operands, modulo 0xffffffffL.

When you are done, cast the result back to int and transmit it.