#utility-class code explainers

java

public final class SensitiveDataMasker {
 
    private static final Pattern CARD_NUMBER = Pattern.compile("\\b(?:\\d[ -]*?){13,19}\\b");
    private static final Pattern EMAIL = Pattern.compile("[A-Za-z0-9._%+-]+@([A-Za-z0-9.-]+\\.[A-Za-z]{2,})");

Masking sensitive data with regex in Java

regex data-masking luhn-algorithm

Intermediate 8 steps

java

public final class CaseConverter {
 
    private static final Pattern CAMEL_BOUNDARY =
            Pattern.compile("([a-z0-9])([A-Z])|([A-Z]+)([A-Z][a-z])");

Converting camelCase to snake_case in Java

regex string-manipulation utility-class

Intermediate 7 steps

java

public final class BomAwareReader {
 
    private static final char UTF8_BOM = '\uFEFF';

Skipping the UTF-8 byte-order mark in Java

file-io encoding byte-order-mark

Intermediate 6 steps

java

public final class DeepCopier {
 
    private static final ObjectMapper MAPPER = new ObjectMapper()
            .registerModule(new JavaTimeModule())

Deep-copying objects via Jackson serialization

serialization deep-copy generics

Intermediate 7 steps

java

public final class IbanValidator {
 
    private static final Map<String, Integer> COUNTRY_LENGTHS = Map.ofEntries(
        Map.entry("DE", 22), Map.entry("FR", 27), Map.entry("GB", 22),

Validating IBANs with the mod-97 checksum

validation checksum modular-arithmetic

Intermediate 8 steps

java

public final class Slugifier {
 
    private static final Pattern NON_LATIN = Pattern.compile("[^\\w-]");
    private static final Pattern WHITESPACE = Pattern.compile("[\\s]+");

Building a URL slugifier in Java

regex unicode-normalization string-processing

Intermediate 8 steps

java

public final class ListPartitioner {
 
    private ListPartitioner() {
    }

Splitting a list into fixed-size chunks in Java

generics partitioning streams

Intermediate 8 steps