Java ByteBuffer

Introduction to Java ByteBuffer

As discussed earlier, the Java bytebuffer is used to hold the sequence of integer values that can be used for I/O operations.

The java bytebuffer class can provide the following operations on the long buffers:

• The java bytebuffer class provides absolute and relative get methods that read single bytes.
• The java bytebuffer class provides absolute and relative put methods that write single bytes.
• The java bytebuffer class provides relative bulk put and get methods that transfer contiguous sequences of bytes from an int array or some other bytes buffer into this buffer and from this buffer into an array.

The java bytebuffer class also provides the following methods to create short buffers:

• allocate(): The java bytebuffer class provides the allocate() method that is used to allocate spaces for the buffer’s content.
• wrap(): The java bytebuffer class provides the wrap() method that is used to wrap an existing long array into a buffer.

Declaration

In this section we will learn how to declare java bytebuffer:

Syntax

Direct vs. Non-direct Buffers

The java bytebuffer can be categorized as either a direct buffer or a non-direct. A direct buffer refers to a buffer's underlying data allocated on a memory area where OS functions can directly access it. A non-direct buffer refers to a buffer whose underlying data is a byte array that is allocated in the Java heap area.

The main difference between direct and non-direct buffers is that in the case of non-direct buffers, the memory location is simply a wrapper around byte array and it resides in Java Heap memory whereas in the case of direct byte buffer the memory location is outside of JVM and memory is not allocated from the heap.

In the case of a direct byte buffer, the native I/O operations are directly performed upon it by the Java virtual machines in order to restrict the duplicity of the content of the buffer to an intermediate buffer before each invocation of one of the underlying operating system's native I/O operations.

Access to Binary Data

This class defines methods for reading and writing values of all other primitive types, except boolean.

The java bytebuffer class helps us to define methods to read and write values for all the primitive types (except for the boolean types). The instance of ByteOrder classes is used to represent specific byte orders. The initial order of a byte buffer is always BIG_ENDIAN.

For access to heterogeneous binary data, that is, sequences of values of different types, this class defines a family of absolute and relative get and put methods for each type.

The java bytebuffer class is used to define a family of relative and absolute put and get methods for access to each type of heterogeneous binary data.

For 32-bit floating-point values, for example, this class defines:

The given methods are defined for primitive data types int, long, short, double, and char.

Invocation Chaining

Methods in this class that do not otherwise have a value to return are specified to return the buffer upon which they are invoked. This allows method invocations to be chained. The sequence of statements

The java bytebuffer allows method invocations to be chained. This happens because methods in this class otherwise do not have a value to return, thus they are specified to return the buffer upon which they are invoked.

The following is the sequence of terms:

Here 'exp' is a java bytebuffer.

Method Summary of Java ByteBuffer

Java ByteBuffer Examples

In this section, we will go through different examples to learn the working of java bytebuffer.

Example 1

In this example, we will try to understand the working of java bytebuffer by creating and displaying a java bytebuffer of a certain size that contains numeric values.

Code:

Output:

Explanation of the example:

In the above example, we are defining the size of the java bytebuffer. After that, we are creating a try-catch block and within the try block, we are defining the bytebuffer object exp and allocating it to the buffer size. Then we are inserting the typecast values using the put method. After that, the buffer is displayed which outputs [10, 20, 30, 40]. The catch block is to check the possibilities of errors and to handle them.

Example 2

In this example, we will try to understand the working of java bytebuffer by creating and displaying a java bytebuffer of a certain size that contains a string.

code:

Output:

Explanation of the example:

In the above example, we are defining the size of the java bytebuffer. After that, we are creating a try-catch block and within the try block, we are defining the bytebuffer object exp and allocating it to the buffer size. Then we are setting the bytebuffer to char inserting a string value using the put method. After that, the buffer is displayed which outputs H e l l o W o r l d. The catch block is to check the possibilities of errors and to handle them.