Package org.apache.tools.ant.filters
Class HeadFilter
- java.lang.Object
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- java.io.Reader
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- java.io.FilterReader
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- org.apache.tools.ant.filters.BaseFilterReader
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- org.apache.tools.ant.filters.BaseParamFilterReader
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- org.apache.tools.ant.filters.HeadFilter
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
,java.lang.Readable
,ChainableReader
,Parameterizable
public final class HeadFilter extends BaseParamFilterReader implements ChainableReader
Reads the firstn
lines of a stream. (Default is first 10 lines.)Example:
<headfilter lines="3"/>
Or:<filterreader classname="org.apache.tools.ant.filters.HeadFilter"> <param name="lines" value="3"/> </filterreader>
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Constructor Summary
Constructors Constructor Description HeadFilter()
Constructor for "dummy" instances.HeadFilter(java.io.Reader in)
Creates a new filtered reader.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description java.io.Reader
chain(java.io.Reader rdr)
Creates a new HeadFilter using the passed in Reader for instantiation.int
read()
Returns the next character in the filtered stream.void
setLines(long lines)
Sets the number of lines to be returned in the filtered stream.void
setSkip(long skip)
Sets the number of lines to be skipped in the filtered stream.-
Methods inherited from class org.apache.tools.ant.filters.BaseParamFilterReader
getParameters, setParameters
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Methods inherited from class org.apache.tools.ant.filters.BaseFilterReader
getInitialized, getProject, read, readFully, readLine, setInitialized, setProject, skip
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Constructor Detail
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HeadFilter
public HeadFilter()
Constructor for "dummy" instances.- See Also:
BaseFilterReader()
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HeadFilter
public HeadFilter(java.io.Reader in)
Creates a new filtered reader.- Parameters:
in
- A Reader object providing the underlying stream. Must not benull
.
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Method Detail
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read
public int read() throws java.io.IOException
Returns the next character in the filtered stream. If the desired number of lines have already been read, the resulting stream is effectively at an end. Otherwise, the next character from the underlying stream is read and returned.- Overrides:
read
in classjava.io.FilterReader
- Returns:
- the next character in the resulting stream, or -1 if the end of the resulting stream has been reached
- Throws:
java.io.IOException
- if the underlying stream throws an IOException during reading
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setLines
public void setLines(long lines)
Sets the number of lines to be returned in the filtered stream.- Parameters:
lines
- the number of lines to be returned in the filtered stream
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setSkip
public void setSkip(long skip)
Sets the number of lines to be skipped in the filtered stream.- Parameters:
skip
- the number of lines to be skipped in the filtered stream
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chain
public java.io.Reader chain(java.io.Reader rdr)
Creates a new HeadFilter using the passed in Reader for instantiation.- Specified by:
chain
in interfaceChainableReader
- Parameters:
rdr
- A Reader object providing the underlying stream. Must not benull
.- Returns:
- a new filter based on this configuration, but filtering the specified reader
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