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reverse order of items in a Java byte[] array

i have a problem reversing the order of items in a bytearray correctly. I want to flip the following String to the one below:
original "\u042F\u0490\u0418\u0432\u0435\u0442"
flipped "\u0442\u0435\u0432\u0418\u0490\u042F"
I tried someonething like this, but this doesn't work.
public byte[] invert(byte[] input) {
ByteBuffer bb = ByteBuffer.wrap(input);
bb.order(ByteOrder.LITTLE_ENDIAN);
byte[] b = bb.array();
return b;
}
any ideas?

This will do what your example shows you're looking for:
String reversed = new StringBuilder(str).reverse().toString();
You may need to decode a byte[] to a String, and then encode the reversed String back to a byte[] using the correct character encoding.

Don't try to treat Unicode characters as bytes! The simplest way to do this is create a String (String(byte[])) get the characters (String.toCharArray()) and write them into a char[] in reverse order, then go back to a byte array via a String again.

How to generate a SecureRandom array, convert it to a string, and then convert it back to array

Here below is how I generate a SecureRandom:
byte[] arr = SecureRandom.getInstance("SHA1PRNG").generateSeed(32);
then, I convert it to a string like this:
String str = new String(arr)
and finally, I try to convert the string back to my original byte array:
byte[] arr2 = str.getBytes()
The problem is that the last statement does not return my original byte array... Am I missing something?

then, I convert it to a string like this:
Don't do that!
You have two problems here:
this constructor will use the default encoding;
even if you used UTF-8 as an encoding, some byte sequences just cannot be encoded to chars!
You should not use String to hold binary data; or use a string-based encoding, such as Base64.
For more information, see CharsetDecoder and CodingErrorAction.

Convert byte array to string with equivalent number of bytes

Is it possible to convert a byte array to a string but where the length of the string is exactly the same length as the number of bytes in the array? If I use the following:
byte[] data; // Fill it with data
data.toString();
The length of the string is different than the length of the array. I believe that this is because Java and/or Android takes some kind of default encoding into account. The values in the array can be negative as well. Theoretically it should be possible to convert any byte to some character. I guess I need to figure out how to specify an encoding that generates a fixed single byte width for each character.
EDIT:
I tried the following but it didn't work:
byte[] textArray; // Fill this with some text.
String textString = new String(textArray, "ASCII");
textArray = textString.getBytes("ASCII"); // textArray ends up with different data.

You can use the String constructor String(byte[] data) to create a string from the byte array. If you want to specify the charset as well, you can use String(byte[] data, Charset charset) constructor.

Try your code sample with US-ASCII or ISO-8859-1 in place of ASCII. ASCII is not a built-in Character encoding for Java or Android, but one of those two are. They are guaranteed single-byte encodings, with a caveat that characters not in the character set will be silently truncated.

This should work fine!
public static byte[] stringToByteArray(String pStringValue){
int length= pStringValue.length();
byte[] bytes = new byte[length];
for(int index=0; index<length; index++){
char ch= pStringValue.charAt(index);
bytes[index]= (byte)ch;
}
return bytes;
}
since JDK 1.6:
You can also use:
stringValue.getBytes() which will return you a byte array.
In case of passing a NULL string, you need to handle that by either throwing the nullPointerException or handling it inside the method itself.

Convert a single byte to a string?

This is simply to error check my code, but I would like to convert a single byte out of a byte array to a string. Does anyone know how to do this? This is what I have so far:
recBuf = read( 5 );
Log.i( TAG, (String)recBuf[0] );
But of course this doesn't work.
I have googled around a bit but have only found ways to convert an entire byte[] array to a string...
new String( recBuf );
I know I could just do that, and then sift through the string, but it would make my task easier if I knew how to operate this way.

You can make a new byte array with a single byte:
new String(new byte[] { recBuf[0] })

Use toString method of Byte
String s=Byte.toString(recBuf[0] );
Try above , it works.
Example:
byte b=14;
String s=Byte.toString(b );
System.out.println("String value="+ s);
Output:
String value=14

There's a String constructor of the form String(byte[] bytes, int offset, int length). You can always use that for your conversion.
So, for example:
byte[] bite = new byte[]{65,67,68};
for(int index = 0; index < bite.length; index++)
System.out.println(new String(bite, index,1));

What about converting it to char? or simply
new String(buffer[0])

public static String toString (byte value)
Since: API Level 1
Returns a string containing a concise, human-readable description of the specified byte value.
Parameters
value the byte to convert to a string.
Returns
a printable representation of value.]1
this is how you can convert single byte to string try code as per your requirement

Edit:
Hows about
""+ recBuf[0];//Hacky... not sure if would work
((Byte)recBuf[0]).toString();
Pretty sure that would work.

Another alternate could be converting byte to char and finally string
Log.i(TAG, Character.toString((char) recBuf[0]));
Or
Log.i(TAG, String.valueOf((char) recBuf[0]));

You're assuming that you're using 8bit character encoding (like ASCII) and this would be wrong for many others.
But with your assumption you might just as well using simple cast to character like
char yourChar = (char) yourByte;
or if really need String:
String string = String.valueOf((char)yourByte);

How to convert from ByteBuffer to Integer and String?

I converted an int to a byte array using ByteBuffer's putInt() method. How do I do the opposite? So convert those bytes to an int?
Furthermore, I converted a string to an array of bytes using the String's getBytes() method. How do I convert it the other way round? The bytesArray.getString() does not return a readable string. I get things like BF#DDAD

You can use the ByteBuffer.getInt method, specifying the offset at which the integer occurs, to convert a series of bytes into an integer. Alternatively, if you happen to know the byte ordering, you can use bitwise operators to explicitly reconstruct the 32-bit integer from its 8-bit octets.
To convert an array of bytes into a String, you can use the String(byte[]) constructor to construct a new String out of the byte array. For example:
byte[] bytes = /* ... get array of bytes ... */
String fromBytes = new String(bytes);