How to use ByteBuffer function for byte operations in Java

ByteBuffer in Java is a class library in Java NIO (New I/O). It can be used to perform byte operations, such as reading data from the network, writing data to the network, and moving data in memory. etc.

The advantage of using the ByteBuffer class is that it provides an efficient way to process large amounts of byte data, and there are many convenient methods to use, such as put(), get(), flip(), clear() and so on. Let’s introduce in detail how to use the ByteBuffer class to perform byte operations.

Create a ByteBuffer object:

First, we need to create a ByteBuffer object. When creating, we need to specify the size of the buffer. You can use the allocate() method of ByteBuffer to create a specified size. The buffer is as follows:

ByteBuffer buffer = ByteBuffer.allocate(1024);

Here we create a ByteBuffer object buffer with a size of 1024 bytes.

Use the put() method to write data to ByteBuffer:

Next, we can use the put() method to write data to ByteBuffer. The put() method has multiple overloaded forms that can write different types of data, as shown below:

buffer.put((byte)0x01); //Write a byte of data
buffer.putChar('a'); //Write a Char type data
buffer.putInt(100); //Write an Int type data
buffer.putFloat(3.5f); // Write a Float type data
buffer.putDouble(2.3); //Write a Double type data

Use the get() method to read data from ByteBuffer:

After writing the data, we can use the get() method to read the data from the ByteBuffer. The get() method also has multiple overloaded forms, which can read different types of data, as shown below:

byte b = buffer.get(); //Read a byte of data
char c = buffer.getChar(); //Read data of type Char
int i = buffer.getInt(); //Read data of type Int
float f = buffer.getFloat(); //Read a Float type data
double d = buffer.getDouble(); //Read a Double type data

Use the flip() method and rewind() method:

After using the put() method to write data to ByteBuffer, you need to pay attention to one thing: after the writing is completed, you must call the flip() method to switch the read and write mode. That is to say, before reading data from ByteBuffer, the flip() method must be called first, as shown below:

buffer.flip();

After calling the flip() method , the read-write pointer of the ByteBuffer object points to the beginning of the buffer. If we want to read data from the beginning of ByteBuffer again, we can use the rewind() method to reset the read and write pointers, as shown below:

buffer.rewind();

Use clear () method:

After reading data from ByteBuffer, if we want to write data to ByteBuffer again, we need to call the clear() method to clear the buffer, as shown below:

buffer.clear();

After calling the clear() method, the read-write pointer of the ByteBuffer object points to the beginning of the buffer, and all data in the buffer is cleared.

Summary:

Through the introduction of this article, we have learned how to use the ByteBuffer class in Java to perform byte operations, including creating a ByteBuffer object and using the put() method to write to ByteBuffer. Data, use the get() method to read data from the ByteBuffer, use the flip() method and rewind() method to switch read and write modes, and use the clear() method to clear the data in the buffer. It should be noted that before performing different operations, you must switch the read and write mode, otherwise the correct data will not be obtained.

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