Java-将byte []转换为int而不给出结果

Question

I have a hexBinary of 4 bytes as follows:

FFFFFFC4

It should return something big but the following function just gives -60:

public static int byteArrayToInt(byte[] b) 
    {
        return   b[3] & 0xFF |
                (b[2] & 0xFF) << 8 |
                (b[1] & 0xFF) << 16 |
                (b[0] & 0xFF) << 24;
    }

Why it doesn't work? Am I doing something wrong?

Answer 1

The primitive type int is 32-bits long and the most significative bit is the sign. The value FFFFFFC4 has the MSB set to 1 , which represents a negative number.

You can get "something big" by using long instead of int :

public static long byteArrayToInt(byte[] b) 
{
    return  (((long) b[3]) & 0xFF) |
            (((long) b[2]) & 0xFF) << 8 |
            (((long) b[1]) & 0xFF) << 16 |
            (((long) b[0]) & 0xFF) << 24;
}