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Buffers are defined in the java.nio package. This package includes several abstract classes that extend Buffer, one for each primitive type except for Boolean: ByteBuffer, CharBuffer, DoubleBuffer, FloatBuffer, IntBuffer, LongBuffer, and ShortBuffer. Buffer defines the core functionality common to all buffers: current position, limit, and capacity. The current position is the index within the buffer at which the next read or write operation will take place.
Scatter and Gather Channels provide an important new capability known as scatter/gather. Scatter/gather is a simple yet powerful concept. It refers to performing a single I/O operation across multiple buffers. For a write operation, data is gathered (drained) from several buffers in turn and sent along the channel. The buffers do not need to have … Read more…
Channels Channels are defined in java.nio.channels. Channels are analogous to streams in the original I/O package. A channel represents an open connection to an Input/Output device, such as a file or a socket. All data that goes anywhere (or comes from anywhere) must pass through a Channel object. In general, to use the NIO system, you obtain … Read more…
Accessing Unsigned Data The Java programming language does not provide direct support for unsigned numeric values (other than char). But there are many instances in which you may need to extract unsigned information from a data stream or file, or pack data to create file headers or other structured information with unsigned fields. The ByteBuffer … Read more…
Put and Get Multibyte Data The ByteBuffer class provides a lightweight mechanism to access groups of bytes as a multibyte data type. ByteBuffer contains setter and getter methods for each of the primitive data types. Setter/Getter methods access the bytes of the ByteBuffer, starting at the current position, as if a data element of that … Read more…
Byte Ordering All primitive types are composed of several bytes: a character or a short integer occupies 2 bytes, a 32-bit integer or a floating-point value occupies 4 bytes, and a long integer or a double precision floating-point value occupies 8 bytes. Each value of one of these multibyte types is stored in a sequence of contiguous memory locations. … Read more…
ByteBuffer to Primitive Buffer When doing high-volume Input/Output, odds are you’ll be using ByteBuffers to read in files, receive data from network connections, etc. Once the data has arrived in your ByteBuffer, you’ll need to look at it to decide what to do or manipulate it before sending it along. The ByteBuffer class provides a … Read more…