---

id: 75

slug: "hex-format"

title: "HexFormat"

category: "datetime"

difficulty: "intermediate"

jdkVersion: "17"

oldLabel: "Java 8"

modernLabel: "Java 17+"

oldApproach: "Manual Hex Conversion"

modernApproach: "HexFormat"

oldCode: |-

// Pad to 2 digits, uppercase

String hex = String.format(

"%02X", byteValue);

// Parse hex string

int val = Integer.parseInt(

"FF", 16);

modernCode: |-

var hex = HexFormat.of()

.withUpperCase();

String s = hex.toHexDigits(

byteValue);

byte[] bytes =

hex.parseHex("48656C6C6F");

summary: "Convert between hex strings and byte arrays with HexFormat."

explanation: "HexFormat provides bidirectional hex encoding/decoding for bytes, ints,\

\ and arrays. Configure delimiters, prefix, suffix, and case. No more manual formatting\

\ or parsing."

whyModernWins:

- icon: "📐"

title: "Bidirectional"

desc: "Convert bytes→hex and hex→bytes with one API."

- icon: "🔧"

title: "Configurable"

desc: "Delimiters, prefix, suffix, upper/lower case."

- icon: "📦"

title: "Array support"

desc: "Encode/decode entire byte arrays at once."

support:

state: "available"

description: "Widely available since JDK 17 LTS (Sept 2021)"

prev: "datetime/math-clamp"

next: "security/pem-encoding"

related:

- "datetime/date-formatting"

- "datetime/instant-precision"

- "datetime/duration-and-period"

docs:

- title: "HexFormat"

href: "https://docs.oracle.com/en/java/javase/25/docs/api/java.base/java/util/HexFormat.html"