Java byte array manipulation

Question

I am trying to select the lower 4 bits of the last byte in a byte array. This is how I have previously done it in PHP but I am new to Java.

$lower4bit = substr($bytes[19], -1);

//Convert the hex to decimal to get the offset value
$offset = hexdec($lower4bit);

//Select the value of the 4 bytes starting at the offset
$joinedArray = implode(array_slice($bytes, $offset, 4));

Can anyone point me in the correct direction with Java?

Answer 1

You access an array like so:

y = a[i];

You find the length of an array like so:

len = a.length;

You can isolate the last 4 bits of an integer like so:

y = x & 0xF;

These should be sufficient to construct the code that you need.