Examples of java.nio.channels.FileChannel.truncate()

java.nio.channels.FileChannel.truncate()
Truncates the file underlying this channel to a given size.
Any bytes beyond the given size are removed from the file. If there are no bytes beyond the given size then the file contents are unmodified.

If the file position is currently greater than the given size, then it is set to be the given size.
@param size the maximum size of the underlying file @throws IllegalArgumentException the requested size is negative. @throws ClosedChannelException the channel is closed. @throws NonWritableChannelException the channel cannot be written. @throws IOException some other IO problem occured. @return this channel

            FileChannel channel = file.getChannel();
            int newsize = random.nextInt((int)channel.size()/2);
            System.out.println("Deliberately truncating file " + 
                               blocks[idx].getName() + 
                               " to size " + newsize + " bytes.");
            channel.truncate(newsize);
            file.close();
          } else {
            //
            // corrupt a few bytes of the metafile
            //

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        File mf = b.getMetaFile();
        // Truncate a block file that has a corresponding metadata file
        if (f.exists() && f.length() != 0 && mf.exists()) {
          FileOutputStream s = new FileOutputStream(f);
          FileChannel channel = s.getChannel();
          channel.truncate(0);
          LOG.info("Truncated block file " + f.getAbsolutePath());
          return b.getBlockId();
        }
      }
    }

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            leftSize = r.nextInt(headerLen);
        } else {
            leftSize = headerLen + r.nextInt(1024 - headerLen);
        }
        FileChannel fc = new RandomAccessFile(fn, "rw").getChannel();
        fc.truncate(leftSize);
        fc.close();
    }


    /**
     * Generate meta entry with given master key

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    // binary, XML, reparsed binary
    String edits = nnHelper.generateEdits();
    FileOutputStream os = new FileOutputStream(edits, true);
    // Corrupt the file by truncating the end
    FileChannel editsFile = os.getChannel();
    editsFile.truncate(editsFile.size() - 5);


    String editsParsedXml = folder.newFile("editsRecoveredParsed.xml")
        .getAbsolutePath();
    String editsReparsed = folder.newFile("editsRecoveredReparsed")
        .getAbsolutePath();

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        File mf = b.getMetaFile();
        // Truncate a block file that has a corresponding metadata file
        if (f.exists() && f.length() != 0 && mf.exists()) {
          FileOutputStream s = new FileOutputStream(f);
          FileChannel channel = s.getChannel();
          channel.truncate(0);
          LOG.info("Truncated block file " + f.getAbsolutePath());
          return b.getBlockId();
        }
      }
    }

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            fileChannel.position(fileChannel.size());
            // FIXME: This worries me a bit, since it could allocate a lot with a large newLength
            fileChannel.write(ByteBuffer.allocate(difference));
        } else {
            fileChannel.truncate(newLength);
        }
        fileChannel.position(position);
    }


    /**

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                long currentSize = channel.size();
                channel.position(0);
                channel.write(ByteBuffer.wrap(baos.toByteArray()));
                if (currentSize > baos.size())
                {
                    channel.truncate(baos.size());
                }
            }
            catch (IOException e)
            {
                throw new IllegalConfigurationException("Cannot store preferences", e);

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                final long length = getCurrentJournalSize();
                final boolean matches = length == (_writeBuffer.position() + _writeBufferAddress) % _blockSize;
                final FileChannel channel = getFileChannel(_currentAddress);
                Debug.$assert1.t(matches);
                if (matches) {
                    channel.truncate(length);
                }
                channel.force(true);
            } catch (final IOException ioe) {
                throw new PersistitIOException(ioe);
            }

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                final long length = getCurrentJournalSize();
                final boolean matches = length == (_writeBuffer.position() + _writeBufferAddress) % _blockSize;
                final FileChannel channel = getFileChannel(_currentAddress);
                Debug.$assert1.t(matches);
                if (matches) {
                    channel.truncate(length);
                }
                channel.force(true);
            } catch (final IOException ioe) {
                throw new PersistitIOException(ioe);
            }

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        byte value = bb.get(pos);
        value--;
        bb.position(pos);
        bb.put(value);
        bb.force();
        fc.truncate(len);
        fc.close();
        return value & 0xFF;
    }
  
    /*

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