org.apache.tools.ant.filters

Class HeadFilter

Implemented Interfaces:
ChainableReader, Parameterizable

public final class HeadFilter
extends BaseParamFilterReader
implements ChainableReader

Reads the first n 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>

Constructor Summary

HeadFilter()
Constructor for "dummy" instances.
HeadFilter(Reader in)
Creates a new filtered reader.

Method Summary

Reader
chain(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

Methods inherited from class org.apache.tools.ant.filters.BaseFilterReader

getInitialized, getProject, read, readFully, readLine, setInitialized, setProject, skip

Constructor Details

HeadFilter

public HeadFilter()
Constructor for "dummy" instances.

HeadFilter

public HeadFilter(Reader in)
Creates a new filtered reader.
Parameters:
in - A Reader object providing the underlying stream. Must not be null.

Method Details

chain

public Reader chain(Reader rdr)
Creates a new HeadFilter using the passed in Reader for instantiation.
Specified by:
chain in interface ChainableReader
Parameters:
rdr - A Reader object providing the underlying stream. Must not be null.
Returns:
a new filter based on this configuration, but filtering the specified reader

read

public int read()
            throws 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.
Returns:
the next character in the resulting stream, or -1 if the end of the resulting stream has been reached

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

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