CharStreams (Guava: Google Core Libraries for Java 15.0 API)

java.lang.Object
- com.google.common.io.CharStreams

```
@Beta
public final class CharStreams
extends Object
```
Provides utility methods for working with character streams.
All method parameters must be non-null unless documented otherwise.
Some of the methods in this class take arguments with a generic type of Readable & Closeable. A Reader implements both of those interfaces. Similarly for Appendable & Closeable and Writer.

Since:

1.0

Author:

Chris Nokleberg, Bin Zhu, Colin Decker

Method Summary

Methods
Modifier and Type	Method and Description
`static CharSink`	`asCharSink(OutputSupplier<? extends Appendable> supplier)` Returns a view of the given `Appendable` supplier as a `CharSink`.
`static CharSource`	`asCharSource(InputSupplier<? extends Readable> supplier)` Returns a view of the given `Readable` supplier as a `CharSource`.
`static CharSource`	`asCharSource(String string)` Deprecated. Use `CharSource.wrap(CharSequence)` instead. This method is scheduled to be removed in Guava 16.0.
`static Writer`	`asWriter(Appendable target)` Returns a Writer that sends all output to the given `Appendable` target.
`static <R extends Readable & Closeable> long`	`copy(InputSupplier<R> from, Appendable to)` Opens a `Readable` object from the supplier, copies all characters to the `Appendable` object, and closes the input.
`static <R extends Readable & Closeable,W extends Appendable & Closeable> long`	`copy(InputSupplier<R> from, OutputSupplier<W> to)` Opens `Readable` and `Appendable` objects from the given factories, copies all characters between the two, and closes them.
`static long`	`copy(Readable from, Appendable to)` Copies all characters between the `Readable` and `Appendable` objects.
`static InputSupplier<Reader>`	`join(InputSupplier<? extends Reader>... suppliers)` Varargs form of `join(Iterable)`.
`static InputSupplier<Reader>`	`join(Iterable<? extends InputSupplier<? extends Reader>> suppliers)` Joins multiple `Reader` suppliers into a single supplier.
`static InputSupplier<InputStreamReader>`	`newReaderSupplier(InputSupplier<? extends InputStream> in, Charset charset)` Returns a factory that will supply instances of `InputStreamReader`, using the given `InputStream` factory and character set.
`static InputSupplier<StringReader>`	`newReaderSupplier(String value)` Returns a factory that will supply instances of `StringReader` that read a string value.
`static OutputSupplier<OutputStreamWriter>`	`newWriterSupplier(OutputSupplier<? extends OutputStream> out, Charset charset)` Returns a factory that will supply instances of `OutputStreamWriter`, using the given `OutputStream` factory and character set.
`static Writer`	`nullWriter()` Returns a `Writer` that simply discards written chars.
`static <R extends Readable & Closeable> String`	`readFirstLine(InputSupplier<R> supplier)` Reads the first line from a `Readable` & `Closeable` object supplied by a factory.
`static <R extends Readable & Closeable> List<String>`	`readLines(InputSupplier<R> supplier)` Reads all of the lines from a `Readable` & `Closeable` object supplied by a factory.
`static <R extends Readable & Closeable,T> T`	`readLines(InputSupplier<R> supplier, LineProcessor<T> callback)` Streams lines from a `Readable` and `Closeable` object supplied by a factory, stopping when our callback returns false, or we have read all of the lines.
`static List<String>`	`readLines(Readable r)` Reads all of the lines from a `Readable` object.
`static <T> T`	`readLines(Readable readable, LineProcessor<T> processor)` Streams lines from a `Readable` object, stopping when the processor returns `false` or all lines have been read and returning the result produced by the processor.
`static void`	`skipFully(Reader reader, long n)` Discards `n` characters of data from the reader.
`static <R extends Readable & Closeable> String`	`toString(InputSupplier<R> supplier)` Returns the characters from a `Readable` & `Closeable` object supplied by a factory as a `String`.
`static String`	`toString(Readable r)` Reads all characters from a `Readable` object into a `String`.
`static <W extends Appendable & Closeable> void`	`write(CharSequence from, OutputSupplier<W> to)` Writes a character sequence (such as a string) to an appendable object from the given supplier.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - newReaderSupplier
```
public static InputSupplier<StringReader> newReaderSupplier(String value)
```
    Returns a factory that will supply instances of StringReader that read a string value.
    
    Parameters:
    value - the string to read
    
    Returns:
    the factory
  - asCharSource
```
@Deprecated
public static CharSource asCharSource(String string)
```
    Deprecated. Use CharSource.wrap(CharSequence) instead. This method is scheduled to be removed in Guava 16.0.
    
    Returns a CharSource that reads the given string value.
    
    Since:
    
    14.0
  - newReaderSupplier
```
public static InputSupplier<InputStreamReader> newReaderSupplier(InputSupplier<? extends InputStream> in,
                                                 Charset charset)
```
    Returns a factory that will supply instances of InputStreamReader, using the given InputStream factory and character set.
    
    Parameters:
    in - the factory that will be used to open input streams
    charset - the charset used to decode the input stream; see Charsets for helpful predefined constants
    
    Returns:
    the factory
  - newWriterSupplier
```
public static OutputSupplier<OutputStreamWriter> newWriterSupplier(OutputSupplier<? extends OutputStream> out,
                                                   Charset charset)
```
    Returns a factory that will supply instances of OutputStreamWriter, using the given OutputStream factory and character set.
    
    Parameters:
    out - the factory that will be used to open output streams
    charset - the charset used to encode the output stream; see Charsets for helpful predefined constants
    
    Returns:
    the factory
  - write
```
public static <W extends Appendable & Closeable> void write(CharSequence from,
                                           OutputSupplier<W> to)
                  throws IOException
```
    Writes a character sequence (such as a string) to an appendable object from the given supplier.
    
    Parameters:
    from - the character sequence to write
    to - the output supplier
    
    Throws:
    
    IOException - if an I/O error occurs
  - copy
```
public static <R extends Readable & Closeable,W extends Appendable & Closeable> long copy(InputSupplier<R> from,
                                                                        OutputSupplier<W> to)
                 throws IOException
```
    Opens Readable and Appendable objects from the given factories, copies all characters between the two, and closes them.
    
    Parameters:
    from - the input factory
    to - the output factory
    
    Returns:
    the number of characters copied
    
    Throws:
    
    IOException - if an I/O error occurs
  - copy
```
public static <R extends Readable & Closeable> long copy(InputSupplier<R> from,
                                        Appendable to)
                 throws IOException
```
    Opens a Readable object from the supplier, copies all characters to the Appendable object, and closes the input. Does not close or flush the output.
    
    Parameters:
    from - the input factory
    to - the object to write to
    
    Returns:
    the number of characters copied
    
    Throws:
    
    IOException - if an I/O error occurs
  - copy
```
public static long copy(Readable from,
        Appendable to)
                 throws IOException
```
    Copies all characters between the Readable and Appendable objects. Does not close or flush either object.
    
    Parameters:
    from - the object to read from
    to - the object to write to
    
    Returns:
    the number of characters copied
    
    Throws:
    
    IOException - if an I/O error occurs
  - toString
```
public static String toString(Readable r)
                       throws IOException
```
    Reads all characters from a Readable object into a String. Does not close the Readable.
    
    Parameters:
    r - the object to read from
    
    Returns:
    a string containing all the characters
    
    Throws:
    
    IOException - if an I/O error occurs
  - toString
```
public static <R extends Readable & Closeable> String toString(InputSupplier<R> supplier)
                       throws IOException
```
    Returns the characters from a Readable & Closeable object supplied by a factory as a String.
    
    Parameters:
    supplier - the factory to read from
    
    Returns:
    a string containing all the characters
    
    Throws:
    
    IOException - if an I/O error occurs
  - readFirstLine
```
public static <R extends Readable & Closeable> String readFirstLine(InputSupplier<R> supplier)
                            throws IOException
```
    Reads the first line from a Readable & Closeable object supplied by a factory. The line does not include line-termination characters, but does include other leading and trailing whitespace.
    
    Parameters:
    supplier - the factory to read from
    
    Returns:
    the first line, or null if the reader is empty
    
    Throws:
    
    IOException - if an I/O error occurs
  - readLines
```
public static <R extends Readable & Closeable> List<String> readLines(InputSupplier<R> supplier)
                              throws IOException
```
    Reads all of the lines from a Readable & Closeable object supplied by a factory. The lines do not include line-termination characters, but do include other leading and trailing whitespace.
    
    Parameters:
    supplier - the factory to read from
    
    Returns:
    a mutable List containing all the lines
    
    Throws:
    
    IOException - if an I/O error occurs
  - readLines
```
public static List<String> readLines(Readable r)
                              throws IOException
```
    Reads all of the lines from a Readable object. The lines do not include line-termination characters, but do include other leading and trailing whitespace.
    Does not close the Readable. If reading files or resources you should use the Files.readLines(java.io.File, java.nio.charset.Charset) and Resources.readLines(java.net.URL, java.nio.charset.Charset, com.google.common.io.LineProcessor<T>) methods.
    
    Parameters:
    r - the object to read from
    
    Returns:
    a mutable List containing all the lines
    
    Throws:
    
    IOException - if an I/O error occurs
  - readLines
```
public static <T> T readLines(Readable readable,
              LineProcessor<T> processor)
                   throws IOException
```
    Streams lines from a Readable object, stopping when the processor returns false or all lines have been read and returning the result produced by the processor. Does not close readable. Note that this method may not fully consume the contents of readable if the processor stops processing early.
    
    Throws:
    
    IOException - if an I/O error occurs
    Since:
    
    14.0
  - readLines
```
public static <R extends Readable & Closeable,T> T readLines(InputSupplier<R> supplier,
                                            LineProcessor<T> callback)
                   throws IOException
```
    Streams lines from a Readable and Closeable object supplied by a factory, stopping when our callback returns false, or we have read all of the lines.
    
    Parameters:
    supplier - the factory to read from
    callback - the LineProcessor to use to handle the lines
    
    Returns:
    the output of processing the lines
    
    Throws:
    
    IOException - if an I/O error occurs
  - join
```
public static InputSupplier<Reader> join(Iterable<? extends InputSupplier<? extends Reader>> suppliers)
```
    Joins multiple Reader suppliers into a single supplier. Reader returned from the supplier will contain the concatenated data from the readers of the underlying suppliers.
    Reading from the joined reader will throw a NullPointerException if any of the suppliers are null or return null.
    Only one underlying reader will be open at a time. Closing the joined reader will close the open underlying reader.
    
    Parameters:
    suppliers - the suppliers to concatenate
    
    Returns:
    a supplier that will return a reader containing the concatenated data
  - join
```
public static InputSupplier<Reader> join(InputSupplier<? extends Reader>... suppliers)
```
    Varargs form of join(Iterable).
  - skipFully
```
public static void skipFully(Reader reader,
             long n)
                      throws IOException
```
    Discards n characters of data from the reader. This method will block until the full amount has been skipped. Does not close the reader.
    
    Parameters:
    reader - the reader to read from
    n - the number of characters to skip
    
    Throws:
    
    EOFException - if this stream reaches the end before skipping all the characters
    
    IOException - if an I/O error occurs
  - nullWriter
```
public static Writer nullWriter()
```
    Returns a Writer that simply discards written chars.
    
    Since:
    
    15.0
  - asWriter
```
public static Writer asWriter(Appendable target)
```
    Returns a Writer that sends all output to the given Appendable target. Closing the writer will close the target if it is Closeable, and flushing the writer will flush the target if it is Flushable.
    
    Parameters:
    target - the object to which output will be sent
    
    Returns:
    a new Writer object, unless target is a Writer, in which case the target is returned
  - asCharSource
```
public static CharSource asCharSource(InputSupplier<? extends Readable> supplier)
```
    Returns a view of the given Readable supplier as a CharSource.
    This method is a temporary method provided for easing migration from suppliers to sources and sinks.
    
    Since:
    
    15.0
  - asCharSink
```
public static CharSink asCharSink(OutputSupplier<? extends Appendable> supplier)
```
    Returns a view of the given Appendable supplier as a CharSink.
    This method is a temporary method provided for easing migration from suppliers to sources and sinks.
    
    Since:
    
    15.0

Class CharStreams

Method Summary

Methods inherited from class java.lang.Object

Method Detail

newReaderSupplier

asCharSource

newReaderSupplier

newWriterSupplier

write

copy

copy

copy

toString

toString

readFirstLine

readLines

readLines

readLines

readLines

join

join

skipFully

nullWriter

asWriter

asCharSource

asCharSink