java.nio

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1. Reading a File into a Buffer

import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.nio.ByteBuffer;

public class ReadFile {

    public static void main(String[] args) throws Exception {
        // Create a new buffer to hold the contents of the file
        ByteBuffer buffer = ByteBuffer.allocate(1024);

        // Read the file into the buffer
        int bytesRead = Files.read(Paths.get("file.txt"), buffer);

        // Create a new byte array to hold the data from the buffer
        byte[] data = new byte[bytesRead];

        // Copy the data from the buffer to the array
        buffer.flip();
        buffer.get(data);

        // Print the data from the array
        System.out.println(new String(data));
    }
}

2. Writing to a File from a Buffer

import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.nio.ByteBuffer;

public class WriteFile {

    public static void main(String[] args) throws Exception {
        // Create a new buffer to hold the data to be written to the file
        ByteBuffer buffer = ByteBuffer.allocate(1024);

        // Put data into the buffer
        buffer.put("Hello, world!".getBytes());

        // Write the buffer to the file
        Files.write(Paths.get("file.txt"), buffer.array(), StandardOpenOption.CREATE);
    }
}

3. Creating a Direct Buffer

import java.nio.ByteBuffer;

public class DirectBuffer {

    public static void main(String[] args) {
        // Create a direct buffer
        ByteBuffer buffer = ByteBuffer.allocateDirect(1024);
    }
}

4. Using a MappedByteBuffer

import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.nio.channels.FileChannel;
import java.nio.MappedByteBuffer;

public class MappedByteBuffer {

    public static void main(String[] args) throws Exception {
        // Open the file and create a channel
        FileChannel channel = Files.newByteChannel(Paths.get("file.txt"), StandardOpenOption.READ);

        // Create a mapped byte buffer
        MappedByteBuffer buffer = channel.map(FileChannel.MapMode.READ_ONLY, 0, channel.size());

        // Read and print the data from the buffer
        for (int i = 0; i < buffer.limit(); i++) {
            byte b = buffer.get(i);
            System.out.print(b);
        }
    }
}

5. Using a FileChannel

import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.nio.channels.FileChannel;
import java.nio.charset.Charset;

public class FileChannel {

    public static void main(String[] args) throws Exception {
        // Open the file and create a channel
        FileChannel channel = Files.newByteChannel(Paths.get("file.txt"), StandardOpenOption.READ);

        // Read and print the data from the channel
        byte[] buffer = new byte[1024];
        while (channel.read(buffer) != -1) {
            String data = new String(buffer, Charset.defaultCharset());
            System.out.print(data);
        }
    }
}

6. Using a CharBuffer

import java.nio.CharBuffer;

public class CharBuffer {

    public static void main(String[] args) {
        // Create a char buffer
        CharBuffer buffer = CharBuffer.allocate(1024);

        // Put data into the buffer
        buffer.put("Hello, world!");

        // Flip the buffer to prepare for reading
        buffer.flip();

        // Print the data from the buffer
        while (buffer.hasRemaining()) {
            char c = buffer.get();
            System.out.print(c);
        }
    }
}

7. Using a DoubleBuffer

import java.nio.DoubleBuffer;

public class DoubleBuffer {

    public static void main(String[] args) {
        // Create a double buffer
        DoubleBuffer buffer = DoubleBuffer.allocate(1024);

        // Put data into the buffer
        buffer.put(1.23);
        buffer.put(4.56);
        buffer.put(7.89);

        // Flip the buffer to prepare for reading
        buffer.flip();

        // Print the data from the buffer
        while (buffer.hasRemaining()) {
            double d = buffer.get();
            System.out.print(d);
        }
    }
}

8. Using a FloatBuffer

import java.nio.FloatBuffer;

public class FloatBuffer {

    public static void main(String[] args) {
        // Create a float buffer
        FloatBuffer buffer = FloatBuffer.allocate(1024);

        // Put data into the buffer
        buffer.put(1.23f);
        buffer.put(4.56f);
        buffer.put(7.89f);

        // Flip the buffer to prepare for reading
        buffer.flip();

        // Print the data from the buffer
        while (buffer.hasRemaining()) {
            float f = buffer.get();
            System.out.print(f);
        }
    }
}

9. Using an IntBuffer

import java.nio.IntBuffer;

public class IntBuffer {

    public static void main(String[] args) {
        // Create an int buffer
        IntBuffer buffer = IntBuffer.allocate(1024);

        // Put data into the buffer
        buffer.put(123);
        buffer.put(456);
        buffer.put(789);

        // Flip the buffer to prepare for reading
        buffer.flip();

        // Print the data from the buffer
        while (buffer.hasRemaining()) {
            int i = buffer.get();
            System.out.print(i);
        }
    }
}

10. Using a LongBuffer

import java.nio.LongBuffer;

public class LongBuffer {

    public static void main(String[] args) {
        // Create a long buffer
        LongBuffer buffer = LongBuffer.allocate(1024);

        // Put data into the buffer
        buffer.put(123L);
        buffer.put(456L);
        buffer.put(789L);

        // Flip the buffer to prepare for reading
        buffer.flip();

        // Print the data from the buffer
        while (buffer.hasRemaining()) {
            long l = buffer.get();
            System.out.print(l);
        }
    }
}

11. Using a ShortBuffer

import java.nio.ShortBuffer;

public class ShortBuffer {

    public static void main(String[] args) {
        // Create a short buffer
        ShortBuffer buffer = ShortBuffer.allocate(1024);

        // Put data into the buffer
        buffer.put((short) 123);
        buffer.put((short) 456);
        buffer.put((short) 789);

        // Flip the buffer to prepare for reading
        buffer.flip();

        // Print the data from the buffer
        while (buffer.hasRemaining()) {
            short s = buffer.get();
            System.out.print(s);
        }
    }
}

12. Using a Buffer

import java.nio.Buffer;

public class Buffer {

    public static void main(String[] args) {
        // Create a buffer
        Buffer buffer = ByteBuffer.allocate(1024);

        // Put data into the buffer
        buffer.put("Hello, world!".getBytes());

        // Flip the buffer to prepare for reading
        buffer.flip();

        // Print the data from the buffer
        byte[] data = new byte[buffer.remaining()];
        buffer.get(data);
        System.out.print(new String(data));
    }
}

13. Using a BufferArray

import java.nio.BufferArray;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;

public class BufferArray {

    public static void main(String[] args) {
        // Create a buffer array
        BufferArray bufferArray = BufferArray.of(
            ByteBuffer.allocate(1024),
            CharBuffer.allocate(1024)
        );

        // Put data into the buffers
        bufferArray.get(0).put("Hello, world!".getBytes());
        bufferArray.get(1).put("Hello, world!");

        // Flip the buffers to prepare for reading
        bufferArray.get(0).flip();
        bufferArray.get(1).flip();

        // Print the data from the buffers
        byte[] data1 = new byte[bufferArray.get(0).remaining()];
        bufferArray.get(0).get(data1);
        System.out.print(new String(data1));

        char[] data2 = new char[bufferArray.get(1).remaining()];
        bufferArray.get(1).get(data2);
        System.out.print(new String(data2));
    }
}

14. Using a HeapByteBuffer

import java.nio.HeapByteBuffer;

public class HeapByteBuffer {

    public static void main(String[] args) {
        // Create a heap byte buffer
        HeapByteBuffer buffer = HeapByteBuffer.allocate(1024);

        // Put data into the buffer
        buffer.put("Hello, world!".getBytes());

        // Flip the buffer to prepare for reading
        buffer.flip();

        // Print the data from the buffer
        byte[] data = new byte[buffer.remaining()];
        buffer.get(data);
        System.out.print(new String(data));
    }
}

15. Using a ByteBufferAsCharBuffer

import java.nio.ByteBuffer;
import java.nio.ByteBufferAsCharBuffer;

public class ByteBufferAsCharBuffer {

    public static void main(String[] args) {
        // Create a byte buffer
        ByteBuffer buffer = ByteBuffer.allocate(1024);

        // Put data into the buffer
        buffer.put("Hello, world!".getBytes());

        // Flip the buffer to prepare for reading
        buffer.flip();

        // Create a char buffer backed by the byte buffer
        ByteBufferAsCharBuffer charBuffer = buffer.asCharBuffer();

        // Print the data from the char buffer
        while (charBuffer.hasRemaining()) {
            char c = charBuffer.get();
            System.out.print(c);
        }
    }
}

16. Using a CharBufferAsByteBuffer

import java.nio.CharBuffer;
import java.nio.CharBufferAsByteBuffer;

public class CharBufferAsByteBuffer {

    public static void main(String[] args) {
        // Create a char buffer
        CharBuffer buffer = CharBuffer.allocate(1024);

        // Put data into the buffer
        buffer.put("Hello, world!");

        // Flip the buffer to prepare for reading
        buffer.flip();

        // Create a byte buffer backed by the char buffer
        CharBufferAsByteBuffer byteBuffer = buffer.asByteBuffer();

        // Print the data from the byte buffer
        byte[] data = new byte[byteBuffer.remaining()];
        byteBuffer.get(data);
        System.out.print(new String(data));
    }
}

17. Using a DoubleBufferAsByteBuffer

import java.nio.DoubleBuffer;
import java.nio.DoubleBufferAsByteBuffer;

public class DoubleBufferAsByteBuffer {

    public static void main(String[] args) {
        // Create a double buffer
        DoubleBuffer buffer = DoubleBuffer.allocate(1024);

        // Put data into the buffer
        buffer.put(1.23);
        buffer.put(4.56);
        buffer.put(7.89);

        // Flip the buffer to prepare for reading
        buffer.flip();

        // Create a byte buffer backed by the double buffer
        DoubleBufferAsByteBuffer byteBuffer = buffer.asByteBuffer();

        // Print the data from the byte buffer
        byte[] data = new byte[byteBuffer.remaining()];
        byteBuffer.get(data);
        System.out.print(new String(data));
    }
}

18. Using a FloatBufferAsByteBuffer

import java.nio.FloatBuffer;
import java.nio.FloatBufferAsByteBuffer;

public class FloatBufferAsByteBuffer {

    public static void main(String[] args) {
        // Create a float buffer
        FloatBuffer buffer = FloatBuffer.allocate(1024);

        // Put data into the buffer
        buffer.put(1.23f);
        buffer.put(4.56f);
        buffer.put(7.89f);

        // Flip the buffer to prepare for reading
        buffer.flip();

        // Create a byte buffer backed by the float buffer
        FloatBufferAsByteBuffer byteBuffer = buffer.asByteBuffer();

        // Print the data from the byte buffer
        byte[] data = new byte[byteBuffer.remaining()];
        byteBuffer.get(data);
        System.out.print(new String(data));
    }
}

19. Using an IntBufferAsByteBuffer

import java.nio.IntBuffer;
import java.nio.IntBufferAsByteBuffer;

public class IntBufferAsByteBuffer {

    public static void main(String[] args) {
        // Create an int buffer
        IntBuffer buffer = IntBuffer.allocate(1024);

        // Put data into the buffer
        buffer