Having in mind portability and simplicity Sun Microsystems created "Write once, run anywhere" (WORA) slogan to illustrate the cross-platform benefits of the Java programming language.
There are two packages in Java API (java.io and java.nio) that handles input and outputthrough data streams, serialization, and the file system. Here is a list of simple examples on Java IO topic.
Java Database Connectivity (JDBC) is an application programming interface (API) for the programming language Java, which defines how a client may access a database. It is part of the Java Standard Edition platform, from Oracle Corporation. JDBC standardises how to connect to a database, how to execute queries, how to navigate the result on a query, and how to execute updates in the database.