Example usage for java.nio ByteBuffer allocate

List of usage examples for java.nio ByteBuffer allocate

  1. HOME
  2. Java
  3. java
  4. java.nio.*
  5. ByteBuffer
  6. allocate

Introduction

In this page you can find the example usage for java.nio ByteBuffer allocate.

Prototype

public static ByteBuffer allocate(int capacity)

Source Link

Document

Creates a byte buffer based on a newly allocated byte array.

Usage

From source file:MainClass.java

public static void main(String[] args) throws Exception {
    createFile();/* www.ja  v a2 s.c  o m*/

    File aFile = new File("C:/primes.bin");
    FileInputStream inFile = new FileInputStream(aFile);

    FileChannel inChannel = inFile.getChannel();

    final int PRIMESREQUIRED = 10;
    ByteBuffer buf = ByteBuffer.allocate(8 * PRIMESREQUIRED);

    long[] primes = new long[PRIMESREQUIRED];
    int index = 0; // Position for a prime in the file

    // Count of primes in the file
    final int PRIMECOUNT = (int) inChannel.size() / 8;

    // Read the number of random primes required
    for (int i = 0; i < PRIMESREQUIRED; i++) {
        index = 8 * (int) (PRIMECOUNT * Math.random());
        inChannel.read(buf, index); // Read the value
        buf.flip();
        primes[i] = buf.getLong(); // Save it in the array
        buf.clear();
    }

    for (long prime : primes) {
        System.out.printf("%12d", prime);
    }
    inFile.close(); // Close the file and the channel

}

From source file:Main.java

public static void main(String[] args) throws Exception {
    Path path = Paths.get("test.txt");

    try (AsynchronousFileChannel afc = AsynchronousFileChannel.open(path, StandardOpenOption.READ)) {
        int fileSize = (int) afc.size();
        ByteBuffer dataBuffer = ByteBuffer.allocate(fileSize);

        Future<Integer> result = afc.read(dataBuffer, 0);
        int readBytes = result.get();

        System.out.format("%s bytes read   from  %s%n", readBytes, path);
        System.out.format("Read data is:%n");

        byte[] byteData = dataBuffer.array();
        Charset cs = Charset.forName("UTF-8");
        String data = new String(byteData, cs);

        System.out.println(data);
    } catch (IOException ex) {
        ex.printStackTrace();/*from w w w .  jav a2s.c o  m*/
    }
}

From source file:Main.java

public static void main(String[] args) throws IOException {

    FileInputStream fin = new FileInputStream(args[0]);
    GZIPInputStream gzin = new GZIPInputStream(fin);
    ReadableByteChannel in = Channels.newChannel(gzin);

    WritableByteChannel out = Channels.newChannel(System.out);
    ByteBuffer buffer = ByteBuffer.allocate(65536);
    while (in.read(buffer) != -1) {
        buffer.flip();//from w  w w.  j a  va  2s .  co m
        out.write(buffer);
        buffer.clear();
    }
}

From source file:BufferConverter.java

public static void main(String[] arguments) {
    try {/*w w  w . ja  v  a  2  s. com*/
        String data = "friends.dat";
        FileInputStream inData = new FileInputStream(data);
        FileChannel inChannel = inData.getChannel();
        long inSize = inChannel.size();
        ByteBuffer source = ByteBuffer.allocate((int) inSize);
        inChannel.read(source, 0);
        source.position(0);
        for (int i = 0; source.remaining() > 0; i++)
            System.out.print(source.get() + " ");

        source.position(0);
        Charset ascii = Charset.forName("US-ASCII");
        CharsetDecoder toAscii = ascii.newDecoder();
        CharBuffer destination = toAscii.decode(source);
        destination.position(0);
        System.out.println("\n\nNew character data:");
        for (int i = 0; destination.remaining() > 0; i++)
            System.out.print(destination.get());
    } catch (Exception ioe) {
        System.out.println(ioe.getMessage());
    }
}

From source file:MainClass.java

public static void main(String[] args) {
    File aFile = new File("afile.txt");
    FileOutputStream outputFile = null;
    try {/*from  w w w.j a  v a 2  s  .  c  om*/
        outputFile = new FileOutputStream(aFile, true);
        System.out.println("File stream created successfully.");
    } catch (FileNotFoundException e) {
        e.printStackTrace(System.err);
    }
    ByteBuffer buf = ByteBuffer.allocate(1024);
    System.out.println("\nByte buffer:");
    System.out.printf("position = %2d  Limit = %4d  capacity = %4d%n", buf.position(), buf.limit(),
            buf.capacity());

    // Create a view buffer
    CharBuffer charBuf = buf.asCharBuffer();
    System.out.println("Char view buffer:");
    System.out.printf("position = %2d  Limit = %4d  capacity = %4d%n", charBuf.position(), charBuf.limit(),
            charBuf.capacity());
    try {
        outputFile.close(); // Close the O/P stream & the channel
    } catch (IOException e) {
        e.printStackTrace(System.err);
    }
}

From source file:Main.java

public static void main(String[] args) {
    File inputFile = new File("test1.txt");
    if (!inputFile.exists()) {
        System.out.println("The input file " + inputFile.getAbsolutePath() + "  does  not  exist.");
        System.out.println("Aborted the   file reading process.");
        return;/* w w w .  ja va2s  .com*/
    }
    try (FileChannel fileChannel = new FileInputStream(inputFile).getChannel()) {
        ByteBuffer buffer = ByteBuffer.allocate(1024);
        while (fileChannel.read(buffer) > 0) {
            buffer.flip();
            while (buffer.hasRemaining()) {
                byte b = buffer.get();
                System.out.print((char) b);
            }
            buffer.clear();
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

From source file:MainClass.java

public static void main(String[] args) {
    File aFile = new File("C:/test.bin");
    FileInputStream inFile = null;
    try {//  ww w.  j a v  a2 s .co  m
        inFile = new FileInputStream(aFile);
    } catch (FileNotFoundException e) {
        e.printStackTrace(System.err);
    }
    FileChannel inChannel = inFile.getChannel();
    final int PRIMECOUNT = 6;
    ByteBuffer buf = ByteBuffer.allocate(8 * PRIMECOUNT);
    long[] primes = new long[PRIMECOUNT];
    try {
        while (inChannel.read(buf) != -1) {
            ((ByteBuffer) (buf.flip())).asLongBuffer().get(primes);
            for (long prime : primes) {
                System.out.printf("%10d", prime);
            }
            buf.clear();
        }
        inFile.close();
    } catch (IOException e) {
        e.printStackTrace(System.err);
    }
}

From source file:MainClass.java

public static void main(String[] args) {
    File aFile = new File("primes.txt");
    FileInputStream inFile = null;
    try {//from   ww  w .j a  v  a2  s  .c  om
        inFile = new FileInputStream(aFile);
    } catch (FileNotFoundException e) {
        e.printStackTrace(System.err);
    }
    FileChannel inChannel = inFile.getChannel();
    try {
        ByteBuffer lengthBuf = ByteBuffer.allocate(8);
        while (true) {
            if (inChannel.read(lengthBuf) == -1) {
                break;
            }
            lengthBuf.flip();
            int strLength = (int) lengthBuf.getDouble();
            ByteBuffer buf = ByteBuffer.allocate(2 * strLength + 8);
            if (inChannel.read(buf) == -1) {
                break;
            }
            buf.flip();
            byte[] strChars = new byte[2 * strLength];
            buf.get(strChars);
            System.out.println(strLength);
            System.out.println(ByteBuffer.wrap(strChars).asCharBuffer());
            System.out.println(buf.getLong());
            lengthBuf.clear();
        }
        inFile.close();
    } catch (IOException e) {
        e.printStackTrace(System.err);
    }
}

From source file:Test.java

public static void main(String[] args) throws Exception {
    Path path = Paths.get("C:/home/docs/users.txt");

    UserDefinedFileAttributeView view = Files.getFileAttributeView(path, UserDefinedFileAttributeView.class);
    view.write("publishable", Charset.defaultCharset().encode("true"));
    System.out.println("Publishable set");

    String name = "publishable";
    ByteBuffer buffer = ByteBuffer.allocate(view.size(name));
    view.read(name, buffer);//from www . j  a v  a2  s. c om
    buffer.flip();
    String value = Charset.defaultCharset().decode(buffer).toString();
    System.out.println(value);

}

From source file:MainClass.java

public static void main(String[] args) {
    File aFile = new File("file.dat");
    FileInputStream inFile = null;

    try {//  ww  w. j  ava 2 s.  c o m
        inFile = new FileInputStream(aFile);
    } catch (FileNotFoundException e) {
        e.printStackTrace(System.err);
        System.exit(0);
    }
    FileChannel inChannel = inFile.getChannel();
    final int COUNT = 6;
    ByteBuffer buf = ByteBuffer.allocate(8 * COUNT);
    long[] data = new long[COUNT];
    try {
        while (inChannel.read(buf) != -1) {
            ((ByteBuffer) (buf.flip())).asLongBuffer().get(data);
            System.out.println();
            for (long prime : data)
                System.out.printf("%10d", prime);
            buf.clear();
        }
        System.out.println("\nEOF reached.");
        inFile.close();
    } catch (IOException e) {
        e.printStackTrace(System.err);
        System.exit(1);
    }
}