CriteriaPattern.java

package com.interview.design.pattern.structural;

import java.util.ArrayList;
import java.util.List;

/**
 * Created_By: stefanie
 * Date: 14-12-3
 * Time: 下午12:35
 * Filter pattern or Criteria pattern is a design pattern that enables developers to filter a set of objects, using different criteria,
 * chaining them in a decoupled way through logical operations.
 */
public class CriteriaPattern {
    static class Person {

        private String name;
        private String gender;
        private String maritalStatus;

        public Person(String name,String gender,String maritalStatus){
            this.name = name;
            this.gender = gender;
            this.maritalStatus = maritalStatus;
        }

        public String getName() {
            return name;
        }
        public String getGender() {
            return gender;
        }
        public String getMaritalStatus() {
            return maritalStatus;
        }
    }

    static interface Criteria {
        public List<Person> meetCriteria(List<Person> persons);
    }

    static class CriteriaMale implements Criteria {

        @Override
        public List<Person> meetCriteria(List<Person> persons) {
            List<Person> malePersons = new ArrayList<Person>();
            for (Person person : persons) {
                if(person.getGender().equalsIgnoreCase("MALE")){
                    malePersons.add(person);
                }
            }
            return malePersons;
        }
    }

    static class CriteriaFemale implements Criteria {

        @Override
        public List<Person> meetCriteria(List<Person> persons) {
            List<Person> femalePersons = new ArrayList<Person>();
            for (Person person : persons) {
                if(person.getGender().equalsIgnoreCase("FEMALE")){
                    femalePersons.add(person);
                }
            }
            return femalePersons;
        }
    }

    static class CriteriaSingle implements Criteria {

        @Override
        public List<Person> meetCriteria(List<Person> persons) {
            List<Person> singlePersons = new ArrayList<Person>();
            for (Person person : persons) {
                if(person.getMaritalStatus().equalsIgnoreCase("SINGLE")){
                    singlePersons.add(person);
                }
            }
            return singlePersons;
        }
    }

    static class AndCriteria implements Criteria {

        private Criteria criteria;
        private Criteria otherCriteria;

        public AndCriteria(Criteria criteria, Criteria otherCriteria) {
            this.criteria = criteria;
            this.otherCriteria = otherCriteria;
        }

        @Override
        public List<Person> meetCriteria(List<Person> persons) {
            List<Person> firstCriteriaPersons = criteria.meetCriteria(persons);
            return otherCriteria.meetCriteria(firstCriteriaPersons);
        }
    }

    static class OrCriteria implements Criteria {

        private Criteria criteria;
        private Criteria otherCriteria;

        public OrCriteria(Criteria criteria, Criteria otherCriteria) {
            this.criteria = criteria;
            this.otherCriteria = otherCriteria;
        }

        @Override
        public List<Person> meetCriteria(List<Person> persons) {
            List<Person> firstCriteriaItems = criteria.meetCriteria(persons);
            List<Person> otherCriteriaItems = otherCriteria.meetCriteria(persons);

            for (Person person : otherCriteriaItems) {
                if(!firstCriteriaItems.contains(person)){
                    firstCriteriaItems.add(person);
                }
            }
            return firstCriteriaItems;
        }
    }

    public static void main(String[] args) {
        List<Person> persons = new ArrayList<Person>();

        persons.add(new Person("Robert","Male", "Single"));
        persons.add(new Person("John","Male", "Married"));
        persons.add(new Person("Laura","Female", "Married"));
        persons.add(new Person("Diana","Female", "Single"));
        persons.add(new Person("Mike","Male", "Single"));
        persons.add(new Person("Bobby","Male", "Single"));

        Criteria male = new CriteriaMale();
        Criteria female = new CriteriaFemale();
        Criteria single = new CriteriaSingle();
        Criteria singleMale = new AndCriteria(single, male);
        Criteria singleOrFemale = new OrCriteria(single, female);

        System.out.println("Males: ");
        printPersons(male.meetCriteria(persons));

        System.out.println("\nFemales: ");
        printPersons(female.meetCriteria(persons));

        System.out.println("\nSingle Males: ");
        printPersons(singleMale.meetCriteria(persons));

        System.out.println("\nSingle Or Females: ");
        printPersons(singleOrFemale.meetCriteria(persons));
    }

    public static void printPersons(List<Person> persons){
        for (Person person : persons) {
            System.out.println("Person : [ Name : " + person.getName()
                    +", Gender : " + person.getGender()
                    +", Marital Status : " + person.getMaritalStatus()
                    +" ]");
        }
    }
}