Package org.apache.tools.ant.filters

Class HeadFilter

java.lang.Object

java.io.Reader

java.io.FilterReader

org.apache.tools.ant.filters.BaseFilterReader

org.apache.tools.ant.filters.BaseParamFilterReader

org.apache.tools.ant.filters.HeadFilter

All Implemented Interfaces:

Closeable, AutoCloseable, Readable, 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>

Field Summary

Fields inherited from class java.io.FilterReader

in

Fields inherited from class java.io.Reader

lock

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method	Description
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

Methods inherited from class java.io.FilterReader

close, mark, markSupported, ready, reset

Methods inherited from class java.io.Reader

nullReader, read, read, transferTo

Methods inherited from class java.lang.Object

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

Constructor Details

HeadFilter

public HeadFilter()

Constructor for "dummy" instances.

See Also:

• BaseFilterReader()

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

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.

Overrides:

read in class FilterReader

Returns:

the next character in the resulting stream, or -1 if the end of the resulting stream has been reached

Throws:

IOException - if the underlying stream throws an IOException during reading

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

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