# Package org.apache.commons.lang

package org.apache.commons.lang
Provides highly reusable static utility methods, chiefly concerned with adding value to the `java.lang` classes.

Since:
  1.0

  Most of these classes are immutable and thus thread-safe. However Charset is not currently guaranteed thread-safe under all circumstances.

Related Packages
Package
Description
org.apache.commons.lang.builder
Assists in creating consistent `equals(Object)`, `toString()`, `hashCode()`, and `compareTo(Object)` methods.
org.apache.commons.lang.enums
Provides an implementation of the C style `enum` in the Java world.
org.apache.commons.lang.exception
Provides JDK 1.4 style Nested Exception functionality for those on prior Java versions.
org.apache.commons.lang.math
Extends `java.math` for business mathematical classes.
org.apache.commons.lang.mutable
Provides typed mutable wrappers to primitive values and Object.
org.apache.commons.lang.reflect
Accumulates common high-level uses of the `java.lang.reflect` APIs.
org.apache.commons.lang.text
Provides classes for handling and manipulating text, partly as an extension to `java.text`.
org.apache.commons.lang.time
Provides classes and methods to work with dates and durations.
Class
Description
ArrayUtils
Operations on arrays, primitive arrays (like `int[]`) and primitive wrapper arrays (like `Integer[]`).
BitField
Operations on bit-mapped fields.
BooleanUtils
Operations on boolean primitives and Boolean objects.
CharEncoding
Character encoding names required of every implementation of the Java platform.
CharRange
A contiguous range of characters, optionally negated.
CharSet
A set of characters.
CharSetUtils
Operations on `CharSet`s.
CharUtils
Operations on char primitives and Character objects.
ClassUtils
Operates on classes without using reflection.
IllegalClassException
Thrown when an object is an instance of an unexpected type (a class or interface).
IncompleteArgumentException
Thrown to indicate an incomplete argument to a method.
LocaleUtils
Operations to assist when working with a `Locale`.
NotImplementedException
Thrown to indicate that a block of code has not been implemented.
NullArgumentException
Thrown to indicate that an argument was `null` and should not have been.
NumberRange
Deprecated.
Use one of the Range classes in org.apache.commons.lang.math.
NumberUtils
Deprecated.
Moved to org.apache.commons.lang.math.
ObjectUtils
Operations on `Object`.
ObjectUtils.Null
Class used as a null placeholder where `null` has another meaning.
RandomStringUtils
Operations for random `String`s.
SerializationException
Exception thrown when the Serialization process fails.
SerializationUtils
Assists with the serialization process and performs additional functionality based on serialization.
StringEscapeUtils
Escapes and unescapes `String`s for Java, Java Script, HTML, XML, and SQL.
StringUtils
Operations on `String` that are `null` safe.
SystemUtils
Helpers for `java.lang.System`.
UnhandledException
Thrown when it is impossible or undesirable to consume or throw a checked exception.
Validate
This class assists in validating arguments.
WordUtils
Operations on Strings that contain words.