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:
java.io.Closeable, java.lang.AutoCloseable, java.lang.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​(java.io.Reader in)
    Creates a new filtered reader.

  • Method Summary

    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

    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​(java.io.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 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 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 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