Read One Character from Different Positions with SeekableByteChannel - Java File Path IO

Java examples for File Path IO:File Channel

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Description

Read One Character from Different Positions with SeekableByteChannel

Demo Code

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.SeekableByteChannel;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.EnumSet;

public class Main {
  public static void main(String[] args) {
    Path path = Paths/* ww  w  . j  av a 2  s . c o  m*/
        .get("C:/folder1/folder2/folder4", "test.txt");
    ByteBuffer buffer = ByteBuffer.allocate(1);
    String encoding = System.getProperty("file.encoding");

    try (SeekableByteChannel seekableByteChannel = (Files.newByteChannel(path,
        EnumSet.of(StandardOpenOption.READ)))) {
      seekableByteChannel.position(0);
      System.out.println("Reading one character from position: "
          + seekableByteChannel.position());
      seekableByteChannel.read(buffer);
      buffer.flip();
      System.out.print(Charset.forName(encoding).decode(buffer));
      buffer.rewind();

      // get into the middle
      seekableByteChannel.position(seekableByteChannel.size() / 2);

      System.out.println("\nReading one character from position: "
          + seekableByteChannel.position());
      seekableByteChannel.read(buffer);
      buffer.flip();
      System.out.print(Charset.forName(encoding).decode(buffer));
      buffer.rewind();

      // get to the end
      seekableByteChannel.position(seekableByteChannel.size() - 1);

      System.out.println("\nReading one character from position: "
          + seekableByteChannel.position());

      seekableByteChannel.read(buffer);
      buffer.flip();
      System.out.print(Charset.forName(encoding).decode(buffer));
      buffer.clear();

    } catch (IOException ex) {
      System.err.println(ex);
    }
  }
}

Result


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