Extract one four-bit digit at a time, beginning at the most significant end of the Java The logical right bit shift
int. A lookup string supplies characters, but no library performs the conversion:java
static String toHex(int value) {
String digits = "0123456789abcdef";
String answer = "";
boolean started = false;
for (int shift = 28; shift >= 0; shift -= 4) {
int digit = (value >>> shift) & 15;
if (started || digit != 0 || shift == 0) {
answer = answer + digits.charAt(digit);
started = true;
}
}
return answer;
}>>> inserts zeros, and the bit mask 15 retains exactly the low four bits of the shifted word. Each emitted character is therefore the corresponding hexadecimal digit. The started flag suppresses leading zero digits; the shift == 0 exception makes zero produce "0", rather than an empty string.A negative Java integer uses two's complement. Its top bit is set, so the first extracted digit is between eight and fifteen and all eight digits are emitted. We interpret its original 32-bit pattern, without taking an absolute value or negating a potentially unnegatable minimum integer. In particular,
toHex(19) returns "13", toHex(-1) returns "ffffffff", and toHex(Integer.MIN_VALUE) returns "80000000". There are exactly eight iterations, so for this fixed word size the time complexity is constant. Articles by others on the same topic
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