Package com.google.common.io

Class CharStreams

  • @Beta
public final class CharStreams
extends java.lang.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

      All Methods Static Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      static CharSink asCharSink​(OutputSupplier<? extends java.lang.Appendable> supplier)
      Deprecated.
      Convert all OutputSupplier<? extends Appendable> implementations to extend CharSink or provide a method for viewing the object as a CharSink.
      static CharSource asCharSource​(InputSupplier<? extends java.lang.Readable> supplier)
      Deprecated.
      Convert all InputSupplier<? extends Readable> implementations to extend CharSource or provide a method for viewing the object as a CharSource.
      static java.io.Writer asWriter​(java.lang.Appendable target)
      Returns a Writer that sends all output to the given Appendable target.
      static long copy​(java.lang.Readable from, java.lang.Appendable to)
      Copies all characters between the Readable and Appendable objects.
      static InputSupplier<java.io.InputStreamReader> newReaderSupplier​(InputSupplier<? extends java.io.InputStream> in, java.nio.charset.Charset charset)
      Deprecated.
      Use ByteSource.asCharSource(Charset) instead.
      static InputSupplier<java.io.StringReader> newReaderSupplier​(java.lang.String value)
      Deprecated.
      Use CharSource.wrap(CharSequence) instead.
      static OutputSupplier<java.io.OutputStreamWriter> newWriterSupplier​(OutputSupplier<? extends java.io.OutputStream> out, java.nio.charset.Charset charset)
      Deprecated.
      Use ByteSink.asCharSink(Charset) instead.
      static java.io.Writer nullWriter()
      Returns a Writer that simply discards written chars.
      static <R extends java.lang.Readable & java.io.Closeable>
      java.lang.String      		 readFirstLine​(InputSupplier<R> supplier)
      Deprecated.
      Use CharSource.readFirstLine() instead.
      static <R extends java.lang.Readable & java.io.Closeable>
      java.util.List<java.lang.String>      		 readLines​(InputSupplier<R> supplier)
      Deprecated.
      Use CharSource.readLines() instead, but note that it returns an ImmutableList.
      static java.util.List<java.lang.String> readLines​(java.lang.Readable r)
      Reads all of the lines from a Readable object.
      static <T> T readLines​(java.lang.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​(java.io.Reader reader, long n)
      Discards n characters of data from the reader.
      static java.lang.String toString​(java.lang.Readable r)
      Reads all characters from a Readable object into a String.

      • Methods inherited from class java.lang.Object

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

    • Method Detail

      • newReaderSupplier

        @Deprecated
public static InputSupplier<java.io.StringReader> newReaderSupplier​(java.lang.String value)
        Deprecated.
        Use CharSource.wrap(CharSequence) instead. This method is scheduled for removal in Guava 18.0.
        Returns a factory that will supply instances of StringReader that read a string value.
        Parameters:
        value - the string to read
        Returns:
        the factory

      • newReaderSupplier

        @Deprecated
public static InputSupplier<java.io.InputStreamReader> newReaderSupplier​(InputSupplier<? extends java.io.InputStream> in,
                                                                         java.nio.charset.Charset charset)
        Deprecated.
        Use ByteSource.asCharSource(Charset) instead. This method is scheduled for removal in Guava 18.0.
        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

        @Deprecated
public static OutputSupplier<java.io.OutputStreamWriter> newWriterSupplier​(OutputSupplier<? extends java.io.OutputStream> out,
                                                                           java.nio.charset.Charset charset)
        Deprecated.
        Use ByteSink.asCharSink(Charset) instead. This method is scheduled for removal in Guava 18.0.
        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

      • copy

        public static long copy​(java.lang.Readable from,
                        java.lang.Appendable to)
                 throws java.io.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:
        java.io.IOException - if an I/O error occurs

      • toString

        public static java.lang.String toString​(java.lang.Readable r)
                                 throws java.io.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:
        java.io.IOException - if an I/O error occurs

      • readFirstLine

        @Deprecated
public static <R extends java.lang.Readable & java.io.Closeable> java.lang.String readFirstLine​(InputSupplier<R> supplier)
                                                                                         throws java.io.IOException
        Deprecated.
        Use CharSource.readFirstLine() instead. This method is scheduled for removal in Guava 18.0.
        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:
        java.io.IOException - if an I/O error occurs

      • readLines

        @Deprecated
public static <R extends java.lang.Readable & java.io.Closeable> java.util.List<java.lang.String> readLines​(InputSupplier<R> supplier)
                                                                                                     throws java.io.IOException
        Deprecated.
        Use CharSource.readLines() instead, but note that it returns an ImmutableList. This method is scheduled for removal in Guava 18.0.
        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:
        java.io.IOException - if an I/O error occurs

      • readLines

        public static <T> T readLines​(java.lang.Readable readable,
                              LineProcessor<T> processor)
                       throws java.io.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:
        java.io.IOException - if an I/O error occurs
        Since:
        14.0

      • skipFully

        public static void skipFully​(java.io.Reader reader,
                             long n)
                      throws java.io.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:
        java.io.EOFException - if this stream reaches the end before skipping all the characters
        java.io.IOException - if an I/O error occurs

      • nullWriter

        public static java.io.Writer nullWriter()
        Returns a Writer that simply discards written chars.
        Since:
        15.0

      • asWriter

        public static java.io.Writer asWriter​(java.lang.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

        @Deprecated
public static CharSource asCharSource​(InputSupplier<? extends java.lang.Readable> supplier)
        Deprecated.
        Convert all InputSupplier<? extends Readable> implementations to extend CharSource or provide a method for viewing the object as a CharSource. This method is scheduled for removal in Guava 18.0.
        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

        @Deprecated
public static CharSink asCharSink​(OutputSupplier<? extends java.lang.Appendable> supplier)
        Deprecated.
        Convert all OutputSupplier<? extends Appendable> implementations to extend CharSink or provide a method for viewing the object as a CharSink. This method is scheduled for removal in Guava 18.0.
        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