2's complement hex number to decimal in java

I have a hex string that represents a 2's complement number. Is there an easy way (libraries/functions) to translate the hex into a decimal without working directly with its bits??

E.G. This is the expected output given the hex on the left:

"0000" => 0
"7FFF" => 32767 (max positive number)
"8000" => -32768 (max negative number)
"FFFF" => -1

Thanks!