Integer to two digits hex in Java

Question

I need to change a integer value into 2-digit hex value in Java.Is there any way for this. Thanks

My biggest number will be 63 and smallest will be 0. I want a leading zero for small values.

Have you at least checked the Integer javadoc? How do you plan to convert 12345656 to a 2-digit hex value? — JB Nizet, Dec 31 '11 at 17:36

score 170 · Accepted Answer · edited May 23 '17 at 11:46

170

String.format("%02X", value);

If you use X instead of x as suggested by aristar, then you don't need to use .toUpperCase().

edited May 23 '17 at 11:46

Community

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answered Oct 10 '13 at 14:10

GabrielOshiro

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This is the best answer at present. – David J. Feb 27 '14 at 22:49
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Agreed this one is much better than any of the others. It works perfectly. The only thing I would suggest is a little more description of the parameters passed to the method. I had to look up if I passed the value as an integer or as a hex string. – JRSofty Mar 25 '14 at 09:10
This unfortunately does not work for strings, you [have to use a little calculation hack](https://stackoverflow.com/a/15635584/3894977) – mrek Sep 30 '21 at 15:20
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I know this is old, but using this method of conversion is extremely slow. If you're doing it in a loop at all, I recommend not using String.format. – Elec0 Sep 21 '22 at 18:02

score 32 · Answer 2 · edited May 23 '17 at 10:31

32

Integer.toHexString(42);

Javadoc: http://docs.oracle.com/javase/6/docs/api/java/lang/Integer.html#toHexString(int)

Note that this may give you more than 2 digits, however! (An Integer is 4 bytes, so you could potentially get back 8 characters.)

Here's a bit of a hack to get your padding, as long as you are absolutely sure that you're only dealing with single-byte values (255 or less):

Integer.toHexString(0x100 | 42).substring(1)

Many more (and better) solutions at Left padding integers (non-decimal format) with zeros in Java.

edited May 23 '17 at 10:31

Community

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answered Dec 31 '11 at 17:35

ziesemer

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Nice zero-padding hack :) – Grodriguez May 09 '14 at 07:45
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You can use the same technique for larger values. If you want padding for up to 2-byte values you can do Integer.toHexString( 0x10000 | value).substring(1). For N hex digits you append N 0s after the "1". Of course, your hex value must have no more than N digits. – user823981 Sep 16 '15 at 22:55

score 31 · Answer 3 · edited Mar 31 '15 at 13:53

31

String.format("%02X", (0xFF & value));

edited Mar 31 '15 at 13:53

Robert

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answered May 23 '13 at 04:30

aristar

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Can someone explain why this is doing a bit-wise and with 0xFF? This is why answers on SO shouldn't just be the code – Stealth Rabbi Jul 26 '13 at 11:48
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OxFF & (byte)value just convert signed byte to unsigned. (int)-1 = 0xFFFFFFFF, (int)(-1 & 0xFf) = 0xFF – aristar Aug 23 '13 at 18:26
In this case, the bit-wise and with 0xFF is not necessary because of the "%02X" format. – Freek de Bruijn May 05 '15 at 14:34
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The %02X specifier specifies a minimum of two digits. If you want exactly two digits (discarding higher bits) then you need the bitwise and. – plugwash Nov 16 '16 at 13:15
Good to know, thanks for this additional information ! – tryp Jan 10 '17 at 15:21

Asaph · Answer 4 · 2011-12-31T17:54:08.513

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Use Integer.toHexString(). Dont forget to pad with a leading zero if you only end up with one digit. If your integer is greater than 255 you'll get more than 2 digits.

StringBuilder sb = new StringBuilder();
sb.append(Integer.toHexString(myInt));
if (sb.length() < 2) {
    sb.insert(0, '0'); // pad with leading zero if needed
}
String hex = sb.toString();

edited Dec 31 '11 at 17:54

answered Dec 31 '11 at 17:41

Asaph

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Is the use of `StringBuilder` actually an improvement? http://pastebin.com/KyS06JMz – just lerning Nov 02 '13 at 10:15

score 4 · Answer 5 · edited Nov 25 '12 at 01:22

4

If you just need to print them try this:

for(int a = 0; a < 255; a++){
    if( a % 16 == 0){
        System.out.println();
    }
    System.out.printf("%02x ", a);
}

edited Nov 25 '12 at 01:22

answered Nov 25 '12 at 00:58

java4loop

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score 1 · Answer 6 · answered May 24 '18 at 12:32

i use this to get a string representing the equivalent hex value of an integer separated by space for every byte EX : hex val of 260 in 4 bytes = 00 00 01 04

    public static String getHexValString(Integer val, int bytePercision){
    StringBuilder sb = new StringBuilder();
    sb.append(Integer.toHexString(val));

    while(sb.length() < bytePercision*2){
        sb.insert(0,'0');// pad with leading zero
    }

    int l = sb.length(); // total string length before spaces
    int r = l/2; //num of rquired iterations

    for (int i=1; i < r;  i++){
        int x = l-(2*i); //space postion
        sb.insert(x, ' ');
    }
    return sb.toString().toUpperCase();         
}

public static void main(String []args){
    System.out.println("hex val of 260 in 4 bytes = " + getHexValString(260,4));
}

score 0 · Answer 7 · answered Jul 07 '20 at 13:57

0

According to GabrielOshiro, If you want format integer to length 8, try this

String.format("0x%08X", 20) //print 0x00000014

answered Jul 07 '20 at 13:57

Victor Choy

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Integer to two digits hex in Java

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