com.myjavatools.lib.foundation
Class Filter<T>

java.lang.Object
  com.myjavatools.lib.foundation.Function<T,java.lang.Boolean>
      com.myjavatools.lib.foundation.Filter<T>

public abstract class Filter<T>
extends Function<T,java.lang.Boolean>

Filter is a Function that returns Boolean values; boolean accept() is an alias for Function.apply(). A good example of Filter is java.io.FileFilter, unfortunately not derived from Filter. To implement this class you should define accept().

Since:

5.0

Version:

6.0 04/28/06

See Also:

Function, Iterator

Constructor Summary

Filter()

Method Summary

abstract boolean	accept(T x) checks whether an object is accepted by the filter
static <T> Filter<T>	and(Filter<T>... filters) Creates conjunction of filters.
java.lang.Boolean	apply(T x) Filter.apply() is the same as accept();
java.lang.Iterable<T>	filter(java.lang.Iterable<T> iterable) filters an Iterable
java.util.Iterator<T>	filter(java.util.Iterator<T> source) Returns filtered iterator
static <T> Filter<T>	not(Filter<T> filter) Creates negation of a filter.
static <T> Filter<T>	or(Filter<T>... filters) Creates disjunction of filters.
static <T> Filter<T>	toFilter(Function<T,java.lang.Double> f) creates a filter that accepts only x such that f(x) > 0

Methods inherited from class com.myjavatools.lib.foundation.Function

apply, apply, apply, compose, compose, forMap, forMap, function, function, id, toMap, toMap

Methods inherited from class java.lang.Object

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

Constructor Detail

Filter

public Filter()

Method Detail

accept

public abstract boolean accept(T x)

checks whether an object is accepted by the filter

Parameters:

x - T an element to check for acceptance

Returns:

boolean true if x is accepted, false otherwise

apply

public java.lang.Boolean apply(T x)

Filter.apply() is the same as accept();

Specified by:

apply in class Function<T,java.lang.Boolean>

Parameters:

x - T an element to which this filter is applied

Returns:

Boolean result of applying this filter to x

toFilter

public static <T> Filter<T> toFilter(Function<T,java.lang.Double> f)

creates a filter that accepts only x such that f(x) > 0

Parameters:

f - Function<T,Double>

Returns:

Filter as defined above

filter

public java.util.Iterator<T> filter(java.util.Iterator<T> source)

Returns filtered iterator

Parameters:

source - Iterator original iterator

Returns:

Iterator filtered iterator the resulting iterator will contain only those elements of source that satisfy this filter

Example:

new Filter<String>() { boolean accept(String s) { return s.startsWith("M"); }}.
 filter(Arrays.asList(new String[] {"New", "Magic", "Logic"}).iterator());
  

returns an iterator returning just "Magic".

filter

public java.lang.Iterable<T> filter(java.lang.Iterable<T> iterable)

filters an Iterable

Parameters:

iterable - Iterable

Returns:

Iterable (view) that contains values that this filter approves

and

public static <T> Filter<T> and(Filter<T>... filters)

Creates conjunction of filters.

Parameters:

filters - (vararg)

Returns:

Filter that returns true only on those x for which all filters return true

or

public static <T> Filter<T> or(Filter<T>... filters)

Creates disjunction of filters.

Returns:

Filter that returns false only on those x for which all filters return false

not

public static <T> Filter<T> not(Filter<T> filter)

Creates negation of a filter.

Parameters:

filter - Filter

Returns:

Filter that returns true on those x for which source filter return false