Convert hex string to int

Question

It's simply too big for an int (which is 4 bytes and signed).

Use

Long.parseLong("AA0F245C", 16);

you may use like that

System.out.println(Integer.decode("0x4d2"))    // output 1234
//and vice versa 
System.out.println(Integer.toHexString(1234); //  output is 4d2);

The maximum value that a Java Integer can handle is 2147483657, or 2^31-1. The hexadecimal number AA0F245C is 2853119068 as a decimal number, and is far too large, so you need to use

Long.parseLong("AA0F245C", 16);

to make it work.

you can easily do it with parseInt with format parameter.

Integer.parseInt("-FF", 16) ; // returns -255

javadoc Integer

This is the right answer:

myPassedColor = "#ffff8c85" int colorInt = Color.parseColor(myPassedColor)

For those of you who need to convert hexadecimal representation of a signed byte from two-character String into byte (which in Java is always signed), there is an example. Parsing a hexadecimal string never gives negative number, which is faulty, because 0xFF is -1 from some point of view (two's complement coding). The principle is to parse the incoming String as int, which is larger than byte, and then wrap around negative numbers. I'm showing only bytes, so that example is short enough.

String inputTwoCharHex="FE"; //whatever your microcontroller data is

int i=Integer.parseInt(inputTwoCharHex,16);
//negative numbers is i now look like 128...255

// shortly i>=128
if (i>=Integer.parseInt("80",16)){

    //need to wrap-around negative numbers
    //we know that FF is 255 which is -1
    //and FE is 254 which is -2 and so on
    i=-1-Integer.parseInt("FF",16)+i;
    //shortly i=-256+i;
}
byte b=(byte)i;
//b is now surely between -128 and +127

This can be edited to process longer numbers. Just add more FF's or 00's respectively. For parsing 8 hex-character signed integers, you need to use Long.parseLong, because FFFF-FFFF, which is integer -1, wouldn't fit into Integer when represented as a positive number (gives 4294967295). So you need Long to store it. After conversion to negative number and casting back to Integer, it will fit. There is no 8 character hex string, that wouldn't fit integer in the end.

An additional option to the ones suggested, is to use the BigInteger class. Since hex values are often large numbers, such as sha256 or sha512 values, they will easily overflow an int and a long. While converting to a byte array is an option as other answers show, BigInterger, the often forgotten class in java, is an option as well.

String sha256 = "65f4b384672c2776116d8d6533c69d4b19d140ddec5c191ea4d2cfad7d025ca2";
BigInteger value = new BigInteger(sha256, 16);
System.out.println("value = " + value);
// 46115947372890196580627454674591875001875183744738980595815219240926424751266