Long to HEX string

Question

I'm having trouble converting a hexadecimal number in a String to a long and then back again. Here's the code I'm using:

private void parseExperiment(){
    String str1 = "AA0F245C";
    long nr = Long.parseLong(str1, 16);
    String str2 = Double.toHexString(nr);
}

I want str2 to be the same as str1 but when I print str1, nr and str2 I get this:

str1: AA0F245C
nr: 2853119068
str2: 0x1.541e48b8p31

Anyone knows how to fix this?