Can you please answer this doubt related to java..
I would like to store MAX_VALUE of unsigned long (i.e 2(pow)64 -1) a n byte array, and then read byte[] array to get back this MAX_VALUE.
As all data types are signed, so would like to know how to store 0xFF (each byte) value in each index of byte[] array i.e ignoring the signed bit. Please suggest on how to do this.
Thanks.
Something like this?
public class Utils {
static byte[] longToByteArray(long value) {
return ByteBuffer.allocate(8).putLong(value).array();
}
static long byteArrayToLong(byte[] array) {
return ByteBuffer.wrap(array).getLong();
}
public static void main(String[] args) {
long maxValue = Long.parseUnsignedLong("FFFFFFFFFFFFFFFF", 16);
byte[] b = longToByteArray(maxValue);
System.out.println("b = " + Arrays.toString(b));
long value = byteArrayToLong(b);
System.out.println("value = " + value);
System.out.println("hex value = " + Long.toUnsignedString(value, 16));
}
}
ByteBuffer is probably better than using DataInputStream /DataOutputStream. Less overhead and you have option of choosing big- vs little-endian mode."FFFFFFFF" is only MAX_UNSIGNED_INT. You need double that, i.e. "FFFFFFFFFFFFFFFF" for MAX_UNSIGNED_LONG.
LongBuffer. Just use putLong and getLong on ByteBuffer, and you can chain it all: return ByteBuffer.allocate(8).putLong(value).array(); and return ByteBuffer.wrap(array).getLong();return ByteBuffer.wrap(array).order(ByteOrder.LITTLE_ENDIAN).getLong();
MAX_VALUEof unsignedlong(i.e 2(pow)64 -1) a n byte array" Ok:byte[] b = {-1, -1, -1, -1, -1, -1, -1, -1}