hex : Java Glossary

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hex

or hexadecimal, base 16 numbers, e.g. 08Cf, made of the digits 0..9 and a..f. This is the number system we would have used had we sixteen fingers instead of ten.

Displaying With Hex Strings

Hex Literals

Hex vs Decimal vs Binary

Table of Hex digits

Hex Color Numbers

Links

Displaying With Hex Strings

You can display in hex using code like this:

That won’t apply any lead zeroes. Here is how to get a lead 0 for a fixed two character hex representation of a byte:

// convert a single byte b to a 2-char hex string
// with possible leading zero.
String s2 = Integer.toString( ( b & 0xff ) + 0x100, 16 /* radix */ ).substring( 1 );

The method com.mindprod.common11.StringTools. toLzHexString will apply the necessary lead zeros for you:

// Available in download http://mindprod.com/products1.html#COMMON11
import com.mindprod.common11.StringTools;
...
// Prepare unsigned hex string padded out to 4 places with lead zeroes.
final String display = StringTools.toHexString( value, 4 /* desired length */ );

You can convert a hex String to internal binary like this:

/* convert a hex String to int */
// Note, there is no lead 0x, case insensitive
String g = "af0c99";
int i = Integer.parseInt( g.trim(), 16 /* radix */ );

The following code looks more complicated, but is considerably faster. It also handles a byte array, not just a single byte.

And here is how to go the other way from a hex string back to a byte array:

Here’s an alternate implementation of charToNibble.

Since the computer uses binary internally, it makes no sense to talk about converting an int from hex to decimal or back, only a String.

Here is how you can convert a String to hex for display so you can tell precisely what each character is.

Use can also use Printwriter.printf( "%x", i ) to display a hex number.

Hex Literals

In Java you can use hex literals like this

// example of a hex 0x literal
int a = 0x8cf;

Hex vs Decimal vs Binary

The computer chip works internally in binary (base 2 numbers), with numbers made only of the digits 0 and 1, low voltage/high voltage. Binary numbers are somewhat bulky to write out, so they are usually written in base 16, hex. It is very easy to convert hex to binary and visa versa using the following table. For example, the hex number 8cf is 100011001111 in binary. Converting between decimal and hex is more difficult. You must do successive divisions and moduluses by 10 or 16.

Table of Hex digits

Decimal	Hex	Binary
0	0	0000
1	1	0001
2	2	0010
3	3	0011
4	4	0100
5	5	0101
6	6	0110
7	7	0111
8	8	1000
9	9	1001
10	a	1010
11	b	1011
12	c	1100
13	d	1101
14	e	1110
15	f	1111

You can handle arbitrarily large hex Strings with BigInteger.

Hex Color Numbers

010 Editor: a hex/binary editor with templates
BigInteger
binary
binary formats
BitSet
conversion
HexView: allows you to view files in hex
Learn To Count Applet to sharpen your intuition on how binary, hex, and octol work
literals
masking
mixed base
octal
PGP hex encoding as words
radix printf
shift
SlickEdit: allows you to view files in hex

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