Package com.google.common.io
Class CharStreams
- java.lang.Object
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- com.google.common.io.CharStreams
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@GwtIncompatible public final class CharStreams extends java.lang.Object
Provides utility methods for working with character streams.Some of the methods in this class take arguments with a generic type of
Readable & Closeable
. AReader
implements both of those interfaces. Similarly forAppendable & Closeable
andWriter
.- Since:
- 1.0
- Author:
- Chris Nokleberg, Bin Zhu, Colin Decker
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static java.io.Writer
asWriter(java.lang.Appendable target)
Returns a Writer that sends all output to the givenAppendable
target.static long
copy(java.lang.Readable from, java.lang.Appendable to)
Copies all characters between theReadable
andAppendable
objects.static long
exhaust(java.lang.Readable readable)
Reads and discards data from the givenReadable
until the end of the stream is reached.static java.io.Writer
nullWriter()
Returns aWriter
that simply discards written chars.static java.util.List<java.lang.String>
readLines(java.lang.Readable r)
Reads all of the lines from aReadable
object.static <T extends @Nullable java.lang.Object>
TreadLines(java.lang.Readable readable, LineProcessor<T> processor)
Streams lines from aReadable
object, stopping when the processor returnsfalse
or all lines have been read and returning the result produced by the processor.static void
skipFully(java.io.Reader reader, long n)
Discardsn
characters of data from the reader.static java.lang.String
toString(java.lang.Readable r)
Reads all characters from aReadable
object into aString
.
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Method Detail
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copy
@CanIgnoreReturnValue public static long copy(java.lang.Readable from, java.lang.Appendable to) throws java.io.IOException
Copies all characters between theReadable
andAppendable
objects. Does not close or flush either object.- Parameters:
from
- the object to read fromto
- the object to write to- Returns:
- the number of characters copied
- Throws:
java.io.IOException
- if an I/O error occurs
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toString
public static java.lang.String toString(java.lang.Readable r) throws java.io.IOException
Reads all characters from aReadable
object into aString
. Does not close theReadable
.- Parameters:
r
- the object to read from- Returns:
- a string containing all the characters
- Throws:
java.io.IOException
- if an I/O error occurs
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readLines
public static java.util.List<java.lang.String> readLines(java.lang.Readable r) throws java.io.IOException
Reads all of the lines from aReadable
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 theFiles.readLines(java.io.File, java.nio.charset.Charset)
andResources.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:
java.io.IOException
- if an I/O error occurs
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readLines
@CanIgnoreReturnValue public static <T extends @Nullable java.lang.Object> T readLines(java.lang.Readable readable, LineProcessor<T> processor) throws java.io.IOException
Streams lines from aReadable
object, stopping when the processor returnsfalse
or all lines have been read and returning the result produced by the processor. Does not closereadable
. Note that this method may not fully consume the contents ofreadable
if the processor stops processing early.- Throws:
java.io.IOException
- if an I/O error occurs- Since:
- 14.0
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exhaust
@CanIgnoreReturnValue public static long exhaust(java.lang.Readable readable) throws java.io.IOException
Reads and discards data from the givenReadable
until the end of the stream is reached. Returns the total number of chars read. Does not close the stream.- Throws:
java.io.IOException
- Since:
- 20.0
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skipFully
public static void skipFully(java.io.Reader reader, long n) throws java.io.IOException
Discardsn
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 fromn
- the number of characters to skip- Throws:
java.io.EOFException
- if this stream reaches the end before skipping all the charactersjava.io.IOException
- if an I/O error occurs
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nullWriter
public static java.io.Writer nullWriter()
Returns aWriter
that simply discards written chars.- Since:
- 15.0
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asWriter
public static java.io.Writer asWriter(java.lang.Appendable target)
Returns a Writer that sends all output to the givenAppendable
target. Closing the writer will close the target if it isCloseable
, and flushing the writer will flush the target if it isFlushable
.- 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
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