Every modern software development stack has one or more well-known common libraries which is not a part of the language core. On the other hand, such general purpose package extends standard set of methods and data structures to professional level of software development. E.g., STL for C++ world. Apache Commons [https://commons.apache.org] is one of the most useful set of general libraries in Java Development. A lot of other packages and frameworks are based on them. In case of new project, Iflexion developers, first of all, to look at Guava [https://code.google.com/p/guava-libraries] — a modern professional implementation of common methods.
Guava is done by Google, freely distributed and supported by Internet giant. They even claim Guava usage in their own projects as a standard. There are 3 main programming languages are used in Google: Java, C++ and Python. Guava is based on Java 6. That makes it useful in legacy projects implemented in terms of Java 6 and needed to support this version. E.g., strings join may be done in Java 8 as String.join(“, “, strings) or by Guava Joiner.on(“, “).join(strings). Guava modules are created with design patterns in mind. There are builders, factory methods, adapters, etc. Guava available via maven/gradle. E.g., for gradle: