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HeadFilter (Apache Ant API)

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:
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>

Author:
Magesh Umasankar

Field Summary
 
Fields inherited from class java.io.FilterReader
in
 
Fields inherited from class java.io.Reader
lock
 
Constructor Summary
HeadFilter()
          Constructor for "dummy" instances.
HeadFilter(java.io.Reader in)
          Creates a new filtered reader.
 
Method Summary
 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.
 
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
read
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

HeadFilter


public HeadFilter()
Constructor for "dummy" instances.

See Also:
BaseFilterReader.BaseFilterReader()

HeadFilter


public HeadFilter(java.io.Reader in)
Creates a new filtered reader.

Parameters:
in - A Reader object providing the underlying stream. Must not be null.
Method Detail

read


public final 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 class java.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

setLines


public final 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

chain


public final java.io.Reader chain(java.io.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


Copyright 2000-2002 Apache Software Foundation. All Rights Reserved.