How to create byte[] from hexadecimal values?

Question

I have the following values:

public static short TAG_VALUE1 = 0x2E09;
public static short TAG_VALUE2 = 0x2E0D;

And I want to create a byte[] from both values. As a byte array, I have to get the first byte and insert it into the array and then the second byte of each TAG. I tried to convert to string and then go back, but I think it has to be an easier way to do so.

How can I get this in a byte[] that looks like this?

2E 09 2E 0D

You need to use bitwise operations to shift the bytes from the short into the byte array: see: en.wikipedia.org/wiki/Bitwise_operation for examples of bitwise operations.. — Nim
– Nim, Commented Jul 28, 2015 at 14:52

Kenney · Accepted Answer · 2015-07-28 14:57:16Z

4

How about

byte[] foo = new byte[] {
    (byte) (TAG_VALUE1>>8),
    (byte) (TAG_VALUE1),
    (byte) (TAG_VALUE2>>8),
    (byte) (TAG_VALUE2),
};

answered Jul 28, 2015 at 14:57

Kenney

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2 Comments

Sonhja Over a year ago

This looks really nice! I tried your code, and it's doing exactly what I asked in a simple way. But when I recover the data, it stores the decimal value of each byte instead of the hexadecimal value of each byte. Any idea?

Jose Cifuentes Over a year ago

The value is the same, what you mean is that Java by default uses the decimal representation of the value when displaying it. If you want to display the hexadecimal values, do this: for (byte b : foo) { System.out.println (String.format("%02x", b)); }

Joop Eggen · Accepted Answer · 2015-07-28 15:01:45Z

2

See ByteBuffer and its many uses.

byte[] bytes = new byte[4];
ByteBuffer buf = ByteBuffer.wrap(bytes);
buf.putShort(TAG_VALUE1);
buf.putShort(TAG_VALUE2);

answered Jul 28, 2015 at 15:01

Joop Eggen

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