Java NIO Tutorial

Java has provided a second I/O system called NIO (New I/O). Java NIO provides the different way of working with I/O than the standard I/O API's. It is an alternate I/O API for Java (from Java 1.4).

It supports a buffer-oriented, channel based approach for I/O operations. With the introduction of JDK 7, the NIO system is expanded, providing the enhanced support for file system features and file-handling. Due to the capabilities supported by the NIO file classes, NIO is widely used in file handling.

NIO was developed to allow Java programmers to implement high-speed I/O without using the custom native code. NIO moves the time-taking I/O activities like filling, namely and draining buffers, etc back into the operating system, thus allows for great increase in operational speed.

Java NIO fundamental components are given below:

• Channels and Buffers: In standard I/O API the character streams and byte streams are used. In NIO we work with channels and buffers. Data is always written from a buffer to a channel and read from a channel to a buffer.
• Selectors: Java NIO provides the concept of "selectors". It is an object that can be used for monitoring the multiple channels for events like data arrived, connection opened etc. Therefore single thread can monitor the multiple channels for data.
• Non-blocking I/O: Java NIO provides the feature of Non-blocking I/O. Here the application returns immediately whatever the data available and application should have pooling mechanism to find out when more data is ready.

Let's see the Application and Operating system interface for Non-blocking I/O: