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I/O

// Read the lines of a UTF-8 text file
ImmutableList<String> lines = Files.asCharSource(file, Charsets.UTF_8)
    .readLines();

// Count distinct word occurrences in a file
Multiset<String> wordOccurrences = HashMultiset.create(
    Splitter.on(CharMatcher.whitespace())
        .trimResults()
        .omitEmptyStrings()
        .split(Files.asCharSource(file, Charsets.UTF_8).read()));

// SHA-1 a file
HashCode hash = Files.asByteSource(file).hash(Hashing.sha1());

// Copy the data from a URL to a file
Resources.asByteSource(url).copyTo(Files.asByteSink(file));

1.ByteStreams and CharStreams

`ByteStreams`	`CharStreams`
`byte[] toByteArray(InputStream)`	`String toString(Readable)`
`N/A`	`List<String> readLines(Readable)`
`long copy(InputStream, OutputStream)`	`long copy(Readable, Appendable)`
`void readFully(InputStream, byte[])`	`N/A`
`void skipFully(InputStream, long)`	`void skipFully(Reader, long)`
`OutputStream nullOutputStream()`	`Writer nullWriter()`

2.Sources and sinks

`Bytes`	`Chars`
`Files.asByteSource(File)`	`Files.asCharSource(File, Charset)`
`Files.asByteSink(File, FileWriteMode...)`	`Files.asCharSink(File, Charset, FileWriteMode...)`
`MoreFiles.asByteSource(Path, OpenOption...)`	`MoreFiles.asCharSource(Path, Charset, OpenOption...)`
`MoreFiles.asByteSink(Path, OpenOption...)`	`MoreFiles.asCharSink(Path, Charset, OpenOption...)`
`Resources.asByteSource(URL)`	`Resources.asCharSource(URL, Charset)`
`ByteSource.wrap(byte[])`	`CharSource.wrap(CharSequence)`
`ByteSource.concat(ByteSource...)`	`CharSource.concat(CharSource...)`
`ByteSource.slice(long, long)`	`N/A`
`CharSource.asByteSource(Charset)`	`ByteSource.asCharSource(Charset)`
`N/A`	`ByteSink.asCharSink(Charset)`

`ByteSource`	`CharSource`
`byte[] read()`	`String read()`
`N/A`	`ImmutableList<String>`	`readLines()`
`N/A`	`String readFirstLine()`
`long copyTo(ByteSink)`	`long copyTo(CharSink)`
`long copyTo(OutputStream)`	`long copyTo(Appendable)`
`Optional<Long> sizeIfKnown()`	`Optional<Long> lengthIfKnown()`
`long size()`	`long length()`
`boolean isEmpty()`	`boolean isEmpty()`
`boolean contentEquals(ByteSource)`	`N/A`
`HashCode hash(HashFunction)`	`N/A`

3.Files

Method	Description
`createParentDirs(File)`	Creates necessary but nonexistent parent directories of the file.
`getFileExtension(String)`	Gets the file extension of the file described by the path.
`getNameWithoutExtension(String)`	Gets the name of the file with its extension removed
`simplifyPath(String)`	Cleans up the path. Not always consistent with your filesystem; test carefully!
`fileTraverser()`	Returns a Traverser that can traverse file trees

4.Closing Resources

4.1try-with-resources

Using JDK7+

try (InputStream in = openInputStream();
     OutputStream out = openOutputStream()) {
  // do stuff with in and out
}

4.2Sources and Sinks

ByteSink sink = ...
Files.asByteSource(file).copyTo(sink);

4.3Closer

Closer closer = Closer.create();
try {
  InputStream in = closer.register(openInputStream());
  OutputStream out = closer.register(openOutputStream());
  // do stuff with in and out
} catch (Throwable e) { // must catch Throwable
  throw closer.rethrow(e);
} finally {
  closer.close();
}

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