A Java collections filter library

This library allows you to filter elements in Java collections using a set of user defined filter rules. You can use any of the pre-defined filter modules that comes with the library or construct a new one by extending Filter interface.

Filtro is available in Maven central repository. Just add the following dependency to your pom.xml and you are good to go.

<dependency>
	<groupId>com.genzis.filtro</groupId>
	<artifactId>filtro</artifactId>
	<version>1.0</version>
</dependency>

Filtro comes pre-built with a class called FilterMap which extends java.util.HashMap internally. You get all features of

HashMap added with the filtering functionality.

Let's construct a FilterMap instance and add some dummy values to it.

FilterMap<Integer,String> map = new FilterMap<Integer,String>();
map.put(1,"Apple");
map.put(2,"Orange");
map.put(3,"Banana");
map.put(4,"Pineapple");
map.put(5,"Grapes");

Filtro comes with a bundle of filter modules. Let's choose NumberRangeFilter which check if the map element is in

between a minimum and maximum number. Constructing a filter is quite simple and straightforward.

Filter<Integer> filter = new NumberRangeFilter<Integer>(2,4);

FilterMap comes with filterKeys and filterValues methods to filter either map keys or values based on the filter or list

of filters specified. For our example we will filter the map keys with the NumberRangeFilter we just constructed.

FilterMap<Integer,String> result = map.filterKeys(filter);

System.out.println(result.toString());

Filter operation will filter key values between 2 and 4(both inclusive). The output of the code will be as below.

{2=Orange,3=Banana,4=Pineapple}

The Full code is as below.

FilterMap<Integer,String> map = new FilterMap<Integer,String>();
map.put(1,"Apple");
map.put(2,"Orange");
map.put(3,"Banana");
map.put(4,"Pineapple");
map.put(5,"Grapes");

Filter<Integer> filter = new NumberRangeFilter<Integer>(2,4);

FilterMap<Integer,String> result = map.filterKeys(filter);

Filtro comes pre-built with a class called FilterList which extends java.util.ArrayList internally. You get all features of

ArrayList added with the filtering functionality.

Let's construct a FilterList instance and add some dummy values to it.

FilterList<Integer> list = new FilterList<Integer>();
list.add(1);
list.add(2);
list.add(3);
list.add(4);
list.add(5);

Let's construct a NumberRangeFilter instance.

Filter<Integer> filter = new NumberRangeFilter<Integer>(2,4);

FilterList comes with filter method to filter list values based on the filter or list

of filters specified. For our example we will filter the list values with the NumberRangeFilter we just constructed.

FilterList<Integer> result = list.filter(filter);

System.out.println(result.toString());

Filter operation will filter list values between 2 and 4(both inclusive). The output of the code will be as below.

[2, 3, 4]

The Full code is as below.

FilterList<Integer> list = new FilterList<Integer>();
list.add(1);
list.add(2);
list.add(3);
list.add(4);
list.add(5);

Filter<Integer> filter = new NumberRangeFilter<Integer>(2,4);

FilterList<Integer> result = list.filter(filter);

Filtro comes pre-built with a class called FilterSet which extends java.util.HashSet internally. You get all features of

HashSet added with the filtering functionality.

Let's construct a FilterSet instance and add some dummy values to it.

FilterSet<Integer> list = new FilterSet<Integer>();
list.add(1);
list.add(2);
list.add(3);
list.add(4);
list.add(5);

Let's construct a NumberRangeFilter instance.

Filter<Integer> filter = new NumberRangeFilter<Integer>(2,4);

FilterSet comes with filter method to filter set values based on the filter or list

of filters specified. For our example we will filter the set values with the NumberRangeFilter we just constructed.

FilterSet<Integer> result = list.filter(filter);

System.out.println(result.toString());

Filter operation will filter set values between 2 and 4(both inclusive). The output of the code will be as below.

[2, 3, 4]

The Full code is as below.

FilterSet<Integer> list = new FilterSet<Integer>();
list.add(1);
list.add(2);
list.add(3);
list.add(4);
list.add(5);

Filter<Integer> filter = new NumberRangeFilter<Integer>(2,4);

FilterSet<Integer> result = list.filter(filter);

You may find a situation where you need to filter map, list or set's values based on multiple filter rules. To facilitate this purpose the filterKeys,filterValues methods in FilterMap and filter method in FilterList and FilterSet also accept a List of filters.

List<Filter<Integer>> filters = new ArrayList<Filter<Integer>>();
filters.add(new NumberMinFilter<Integer>(2));
filters.add(new NumberMaxFilter<Integer>(5));

FilterList<Integer> result = list.filter(filters);

Filtro doesn't restrict you to use our implementations such as FilterMap,FilterList and FilterSet. You can use any desired implementation of Map,'List' and Set interfaces and still filter it using our library. The Filters class contains several static methods to filter any implementation of java collections. Let's construct a LinkedHashMap and filter it using the Filters class.

Map<Integer,String> map = new LinkedHashMap<Integer,String>();
map.put(1,"Apple");
map.put(2,"Orange");
map.put(3,"Banana");
map.put(4,"Pineapple");
map.put(5,"Grapes");

List<Filter<Integer>> filters = new ArrayList<Filter<Integer>>();
filters.add(new NumberRangeFilter<Integer>(2,4));

Map<Integer,String> result = Filters.filterMapKeys(map,filters,false);

The first parameter is the map which you need to filter. The second parameter is the list of filters based on which map keys should be filtered. The third parameter is a boolean flag indicating whether the original map should be modified or just a new copy should be returned. If true the elements which fails filter test will be removed in the original map itself. If false the original map will remain unchanged and you can obtain the filter result as return value from the method.

You can create a custom filter rule by extending the Filter interface.

import com.genzis.filtro.Filter;

class TestFilter implements Filter<String> {
	private String condition;
	
	//Optional: Only needed if you need to check the collection value with something. 
	public TestFilter(String condition) {
		this.condition = condition;
	}
	
	//implements the check method of Filter interface.
	public boolean check(String value) {
		//Execute any condition and return true or false.
	}
}

• If you find any bug or need any new feature, please open an issue in Github. I will try my best to reply back as soon as possible.
• If you wish to contribute to the code, fork the repo, commit any changes and send pull request.

The MIT License (MIT)

Copyright (c) 2013 Genzis

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.