Commons Lang

Apache Commons Lang is a set of utility classes that extend the java.util package and they make the life of a Java developer a lot easier by providing many little methods that solve common problems and save a lot of time.

To include external libraries in Java, we usually use Maven, which makes it very easy to manage dependencies. With Maven, the Apache Commons Lang library can be included using this dependency snippet:

<dependency> 
  <groupId>org.apache.commons</groupId> 
  <artifactId>commons-lang3</artifactId> 
  <version>3.4</version> 
</dependency>

The library contains a lot of methods useful for general-purpose Java programming, such as making it easier to implement the equals and hashCode methods for objects, serialization helpers and others. In general, they are not very specific to data science, but there are a few helper functions that are quite useful. For example,

• RandomUtils and RandomStringUtils for generating data
• StringEscapeUtils and LookupTranslator for escaping and un-escaping strings
• EqualsBuilder and HashCodeBuilder for the fast implementation of equals and hashCode methods
• StringUtils and WordUtils for useful string manipulation methods
• the Pair class

For more information, you can read the documentation at https://commons.apache.org/lang.

The best way to see what is available is to download the package and see the code available there. Every Java developer will find a lot of useful things.