org.apache.tools.ant.filters

Class SortFilter

public final class SortFilter extends BaseParamFilterReader implements ChainableReader

Sort a file before and/or after the file.

Examples:

   <copy todir="build">
       <fileset dir="input" includes="*.txt"/>
       <filterchain>
           <sortfilter/>
       </filterchain>
   </copy>
 

Sort all files *.txt from src location and copy them into build location. The lines of each file are sorted in ascendant order comparing the lines via the String.compareTo(Object o) method.

   <copy todir="build">
       <fileset dir="input" includes="*.txt"/>
       <filterchain>
           <sortfilter reverse="true"/>
       </filterchain>
   </copy>
 

Sort all files *.txt from src location into reverse order and copy them into build location. If reverse parameter has value true (default value), then the output line of the files will be in ascendant order.

   <copy todir="build">
       <fileset dir="input" includes="*.txt"/>
       <filterchain>
           <filterreader classname="org.apache.tools.ant.filters.SortFilter">
             <param name="comparator" value="org.apache.tools.ant.filters.EvenFirstCmp"/>
           </filterreader>
       </filterchain>
   </copy>
 

Sort all files *.txt from src location using as sorting criterium EvenFirstCmp class, that sorts the file lines putting even lines first then odd lines for example. The modified files are copied into build location. The EventFirstCmp, has to an instanciable class via Class.newInstance(), therefore in case of inner class has to be static. It also has to implement java.util.Comparator interface, for example:

         package org.apache.tools.ant.filters;
         ...(omitted)
           public final class EvenFirstCmp implements <b>Comparator</b> {
             public int compare(Object o1, Object o2) {
             ...(omitted)
             }
           }
 

The example above is equivalent to:

   <componentdef name="evenfirst"
                 classname="org.apache.tools.ant.filters.EvenFirstCmp"/>
   <copy todir="build">
       <fileset dir="input" includes="*.txt"/>
       <filterchain>
           <sortfilter>
               <evenfirst/>
           </sortfilter>
       </filterchain>
   </copy>
 

If parameter comparator is present, then reverse parameter will not be taken into account.

Since: Ant 1.8.0

Constructor Summary
SortFilter()
Constructor for "dummy" instances.
SortFilter(Reader in)
Creates a new filtered reader.
Method Summary
voidadd(Comparator comparator)
Set the comparator to be used as sorting criterium as nested element.
Readerchain(Reader rdr)
Creates a new SortReader using the passed in Reader for instantiation.
ComparatorgetComparator()
Returns the comparator to be used for sorting.
booleanisReverse()
Returns true if the sorting process will be in reverse order, otherwise the sorting process will be in ascendant order.
intread()
Returns the next character in the filtered stream.
voidsetComparator(Comparator comparator)
Set the comparator to be used as sorting criterium.
voidsetReverse(boolean reverse)
Sets the sorting process will be in ascendant (reverse=false) or to descendant (reverse=true).

Constructor Detail

SortFilter

public SortFilter()
Constructor for "dummy" instances.

See Also: BaseFilterReader

SortFilter

public SortFilter(Reader in)
Creates a new filtered reader.

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

Method Detail

add

public void add(Comparator comparator)
Set the comparator to be used as sorting criterium as nested element.

Parameters: comparator the comparator to set

chain

public Reader chain(Reader rdr)
Creates a new SortReader using the passed in Reader for instantiation.

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

getComparator

public Comparator getComparator()
Returns the comparator to be used for sorting.

Returns: the comparator

isReverse

public boolean isReverse()
Returns true if the sorting process will be in reverse order, otherwise the sorting process will be in ascendant order.

Returns: true if the sorting process will be in reverse order, otherwise the sorting process will be in ascendant order.

read

public int read()
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

Throws: IOException if the underlying stream throws an IOException during reading

setComparator

public void setComparator(Comparator comparator)
Set the comparator to be used as sorting criterium.

Parameters: comparator the comparator to set

setReverse

public void setReverse(boolean reverse)
Sets the sorting process will be in ascendant (reverse=false) or to descendant (reverse=true).

Parameters: reverse Boolean representing reverse ordering process.