java.util.AbstractCollection<MutableString>

it.unimi.dsi.io.FileLinesCollection

All Implemented Interfaces:: Iterable<MutableString>, Collection<MutableString>

public class FileLinesCollection
extends AbstractCollection<MutableString>

A wrapper exhibiting the lines of a file as a Collection.

Warning: the lines returned by iterators generated by instances of this class are not cacheable. The returned value is a MutableString instance that is reused at each call, and that is modified by a call to hasNext(). Thus, for instance,

    ObjectIterators.unwrap(fileLinesColletion.iterator());

will not give the expected results. Use allLines() to get the list of all lines (again, under the form of compact MutableStrings). Note also that toString() will return a single string containing all file lines separated by the string associated with the system property line.separator.

An instance of this class allows to access the lines of a file as a Collection. Using direct access is strongly discouraged (it will require a full scan of the file), but the iterator() can be fruitfully used to scan the file, and can be called any number of times, as it opens an independent input stream at each call. For the same reason, the returned iterator type (FileLinesCollection.FileLinesIterator) is Closeable, and should be closed after usage.

Using a suitable constructor, it is possible to specify that the file is compressed in gzip format (in this case, it will be opened using a GZIPInputStream).

Note that the first call to size() will require a full file scan.

Since:: 0.9.2
Author:: Sebastiano Vigna

Nested Class Summary

Nested Classes

Modifier and Type Class Description

static class FileLinesCollection.FileLinesIterator
An iterator over the lines of a FileLinesCollection.

Constructor Summary

Constructors
Constructor	Description
`FileLinesCollection(CharSequence filename, String encoding)`	Creates a file-lines collection for the specified filename with the specified encoding.
`FileLinesCollection(CharSequence filename, String encoding, boolean zipped)`	Creates a file-lines collection for the specified filename with the specified encoding, optionally assuming that the file is compressed using `gzip` format.

Method Summary

Modifier and Type	Method	Description
`ObjectList<MutableString>`	`allLines()`	Returns all lines of the file wrapped by this file-lines collection.
`FileLinesCollection.FileLinesIterator`	`iterator()`
`int`	`size()`
`Object[]`	`toArray()`
`<T> T[]`	`toArray(T[] a)`
`String`	`toString()`

Methods inherited from class java.util.AbstractCollection

add, addAll, clear, contains, containsAll, isEmpty, remove, removeAll, retainAll

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Collection

equals, hashCode, parallelStream, removeIf, spliterator, stream, toArray

Methods inherited from interface java.lang.Iterable

forEach

Constructor Details
- FileLinesCollection
  
  public FileLinesCollection(CharSequence filename, String encoding)
  
  Creates a file-lines collection for the specified filename with the specified encoding.
  
  Parameters:
  
  filename - a filename.
  
  encoding - an encoding.
- FileLinesCollection
  
  public FileLinesCollection(CharSequence filename, String encoding, boolean zipped)
  
  Creates a file-lines collection for the specified filename with the specified encoding, optionally assuming that the file is compressed using gzip format.
  
  Parameters:
  
  filename - a filename.
  
  encoding - an encoding.
  
  zipped - whether filename is zipped.
Method Details
- iterator
  
  public FileLinesCollection.FileLinesIterator iterator()
  
  Specified by:
  
  iterator in interface Collection<MutableString>
  
  Specified by:
  
  iterator in interface Iterable<MutableString>
  
  Specified by:
  
  iterator in class AbstractCollection<MutableString>
- size
  
  public int size()
  
  Specified by:
  
  size in interface Collection<MutableString>
  
  Specified by:
  
  size in class AbstractCollection<MutableString>
- allLines
  
  public ObjectList<MutableString> allLines()
  
  Returns all lines of the file wrapped by this file-lines collection.
  
  Returns:
  
  all lines of the file wrapped by this file-lines collection.
- toArray
  
  public Object[] toArray()
  
  Specified by:
  
  toArray in interface Collection<MutableString>
  
  Overrides:
  
  toArray in class AbstractCollection<MutableString>
- toArray
  
  public <T> T[] toArray(T[] a)
  
  Specified by:
  
  toArray in interface Collection<MutableString>
  
  Overrides:
  
  toArray in class AbstractCollection<MutableString>
- toString
  
  public String toString()
  
  Overrides:
  
  toString in class AbstractCollection<MutableString>

Class FileLinesCollection

Nested Class Summary