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🏷 Formatting 4 patterns

Topic: Formatting

All Java patterns related to Formatting — java.evolved

String.indent() and transform()

Old String[] lines = text.split("\n"); StringBuilder sb = new StringBuilder(); for (String line : lines) { sb.append(" ").append(line) .append("\n"); } String indented = sb.toString();

Modern String indented = text.indent(4); String result = text .transform(String::strip) .transform(s -> s.replace(" ", "-"));

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JDK 12+ learn more →

String.formatted()

Old String msg = String.format( "Hello %s, you are %d", name, age );

Modern String msg = "Hello %s, you are %d" .formatted(name, age);

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JDK 15+ learn more →

Date formatting

Old // Not thread-safe! SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd"); String formatted = sdf.format(date); // Must synchronize for concurrent use

Modern DateTimeFormatter fmt = DateTimeFormatter.ofPattern( "uuuu-MM-dd"); String formatted = LocalDate.now().format(fmt); // Thread-safe, immutable

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JDK 8+ learn more →

HexFormat

Old // Pad to 2 digits, uppercase String hex = String.format( "%02X", byteValue); // Parse hex string int val = Integer.parseInt( "FF", 16);

Modern var hex = HexFormat.of() .withUpperCase(); String s = hex.toHexDigits( byteValue); byte[] bytes = hex.parseHex("48656C6C6F");

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JDK 17+ learn more →