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At a glance

1. 1StringUtils.isBlank(s) is true for null, empty or only spaces; StringUtils.isEmpty, trimToEmpty, capitalize, join, leftPad, substringBetween, defaultIfBlank, abbreviate avoid null checks
2. 2CollectionUtils.isEmpty(c) handles null; MapUtils.isNotEmpty(m); ArrayUtils.contains(arr, x); ObjectUtils.defaultIfNull; NumberUtils.toInt("x", 0) parses with a default instead of throwing
3. 3FileUtils.readFileToString(f, UTF_8), FileUtils.copyDirectory, IOUtils.toString(in, UTF_8), IOUtils.closeQuietly cover file and stream chores
4. 4EqualsBuilder, HashCodeBuilder, ToStringBuilder build equals, hashCode and toString from fields; Pair.of(a, b) is a simple pair; commons-csv (CSVFormat.DEFAULT.parse(reader)) reads CSV with quotes and escapes correctly

• Many helpers now have JDK equivalents: String.isBlank(), strip(), Objects.equals, Objects.hash, Files.readString, records and Lombok instead of the *Builder classes
• Do not parse CSV with line.split(","): quoted fields containing commas and line breaks break it
• They are plain static methods written for null safety and edge cases; the reflection-based builders (EqualsBuilder.reflectionEquals) are slow and best avoided in hot code

import org.apache.commons.lang3.StringUtils;import org.apache.commons.lang3.math.NumberUtils;import org.apache.commons.collections4.CollectionUtils;import java.util.List;public class Clean {  static String name(String raw) { return StringUtils.capitalize(StringUtils.trimToEmpty(raw).toLowerCase()); }  static boolean missing(String s) { return StringUtils.isBlank(s); }  static int qty(String s) { return NumberUtils.toInt(s, 1); }  static boolean empty(List<String> items) { return CollectionUtils.isEmpty(items); }}

1. line 1 uses StringUtils, the core of Apache Commons helpers
2. line 2 uses NumberUtils, the core of Apache Commons helpers
3. line 3 uses CollectionUtils, the core of Apache Commons helpers
4. line 6 uses StringUtils, the core of Apache Commons helpers
5. line 7 uses StringUtils, the core of Apache Commons helpers
6. line 8 uses NumberUtils, the core of Apache Commons helpers

How Unravel recognises it

When you paste code, Unravel looks for these signs of apache commons helpers. Spotting them yourself is a good habit when you read unfamiliar code:

• Types: StringUtils CollectionUtils ObjectUtils NumberUtils IOUtils FileUtils ArrayUtils DateUtils Validate RandomStringUtils SystemUtils MapUtils EqualsBuilder HashCodeBuilder and 8 more

Part of a learning path

• JDBC and everyday libraries · previous: Guava utilities · next: MapStruct and object mapping

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