Package org.apache.commons.io.input
Class NullReader
java.lang.Object
java.io.Reader
org.apache.commons.io.input.NullReader
- All Implemented Interfaces:
Closeable,AutoCloseable,Readable
A functional, light weight
Reader that emulates
a reader of a specified size.
This implementation provides a light weight
object for testing with an Reader
where the contents don't matter.
One use case would be for testing the handling of
large Reader as it can emulate that
scenario without the overhead of actually processing
large numbers of characters - significantly speeding up
test execution times.
This implementation returns a space from the method that
reads a character and leaves the array unchanged in the read
methods that are passed a character array.
If alternative data is required the processChar() and
processChars() methods can be implemented to generate
data, for example:
public class TestReader extends NullReader {
public TestReader(int size) {
super(size);
}
protected char processChar() {
return ... // return required value here
}
protected void processChars(char[] chars, int offset, int length) {
for (int i = offset; i < length; i++) {
chars[i] = ... // set array value here
}
}
}
- Since:
- 1.3
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Field Summary
Fields -
Constructor Summary
ConstructorsConstructorDescriptionConstructs aReaderthat emulates a size 0 reader which supports marking and does not throw EOFException.NullReader(long size) Constructs aReaderthat emulates a specified size which supports marking and does not throw EOFException.NullReader(long size, boolean markSupported, boolean throwEofException) Constructs aReaderthat emulates a specified size with option settings. -
Method Summary
Modifier and TypeMethodDescriptionvoidclose()Closes this Reader - resets the internal state to the initial values.longReturns the current position.longgetSize()Returns the size thisReaderemulates.voidmark(int readLimit) Marks the current position.booleanIndicates whether mark is supported.protected intReturns a character value for theread()method.protected voidprocessChars(char[] chars, int offset, int length) Process the characters for theread(char[], offset, length)method.intread()Reads a character.intread(char[] chars) Reads some characters into the specified array.intread(char[] chars, int offset, int length) Reads the specified number characters into an array.voidreset()Resets the stream to the point when mark was last called.longskip(long numberOfChars) Skips a specified number of characters.
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Field Details
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INSTANCE
The singleton instance.- Since:
- 2.12.0
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Constructor Details
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NullReader
public NullReader()Constructs aReaderthat emulates a size 0 reader which supports marking and does not throw EOFException.- Since:
- 2.7
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NullReader
Constructs aReaderthat emulates a specified size which supports marking and does not throw EOFException.- Parameters:
size- The size of the reader to emulate.
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NullReader
Constructs aReaderthat emulates a specified size with option settings.- Parameters:
size- The size of the reader to emulate.markSupported- Whether this instance will support themark()functionality.throwEofException- Whether this implementation will throw anEOFExceptionor return -1 when the end of file is reached.
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Method Details
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close
Closes this Reader - resets the internal state to the initial values.- Specified by:
closein interfaceAutoCloseable- Specified by:
closein interfaceCloseable- Specified by:
closein classReader- Throws:
IOException- If an error occurs.
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getPosition
Returns the current position.- Returns:
- the current position.
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getSize
Returns the size thisReaderemulates.- Returns:
- The size of the reader to emulate.
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mark
Marks the current position.- Overrides:
markin classReader- Parameters:
readLimit- The number of characters before this marked position is invalid.- Throws:
UnsupportedOperationException- if mark is not supported.
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markSupported
Indicates whether mark is supported.- Overrides:
markSupportedin classReader- Returns:
- Whether mark is supported or not.
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processChar
Returns a character value for theread()method.This implementation returns zero.
- Returns:
- This implementation always returns zero.
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processChars
Process the characters for theread(char[], offset, length)method.This implementation leaves the character array unchanged.
- Parameters:
chars- The character arrayoffset- The offset to start at.length- The number of characters.
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read
Reads a character.- Overrides:
readin classReader- Returns:
- Either The character value returned by
processChar()or-1if the end of file has been reached andthrowEofExceptionis set tofalse. - Throws:
EOFException- if the end of file is reached andthrowEofExceptionis set totrue.IOException- if trying to read past the end of file.
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read
Reads some characters into the specified array.- Overrides:
readin classReader- Parameters:
chars- The character array to read into- Returns:
- The number of characters read or
-1if the end of file has been reached andthrowEofExceptionis set tofalse. - Throws:
EOFException- if the end of file is reached andthrowEofExceptionis set totrue.IOException- if trying to read past the end of file.
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read
Reads the specified number characters into an array.- Specified by:
readin classReader- Parameters:
chars- The character array to read into.offset- The offset to start reading characters into.length- The number of characters to read.- Returns:
- The number of characters read or
-1if the end of file has been reached andthrowEofExceptionis set tofalse. - Throws:
EOFException- if the end of file is reached andthrowEofExceptionis set totrue.IOException- if trying to read past the end of file.
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reset
Resets the stream to the point when mark was last called.- Overrides:
resetin classReader- Throws:
UnsupportedOperationException- if mark is not supported.IOException- If no position has been marked or the read limit has been exceeded since the last position was marked.
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skip
Skips a specified number of characters.- Overrides:
skipin classReader- Parameters:
numberOfChars- The number of characters to skip.- Returns:
- The number of characters skipped or
-1if the end of file has been reached andthrowEofExceptionis set tofalse. - Throws:
EOFException- if the end of file is reached andthrowEofExceptionis set totrue.IOException- if trying to read past the end of file.
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