Coherence: Collections Filter

Recently, I was working on an API where I needed to get the coherence cache values based on a filter which can filter the attributes in the collection. I verified coherence APIs and found ContainsFilter but it would only check whether the whole object(Like String, Integer) is in the collection or not, but wouldn't filter the user-defined beans.

So, I came up with the below CollectionsAwareFilter where we can filter the bean attributes lying inside of a list—or list of a list of a list...

I am posting the code here... please feel free to copy it if you'd like. And of course, any suggestions for improvement or alternate (easier) ways would be much appreciated.

package coh.collections.filter;

import com.tangosol.util.Filter;
import com.tangosol.util.ValueExtractor;
import com.tangosol.util.filter.ComparisonFilter;

import java.util.Collection;

/**
 * <pre>
 * Filter which tests a Collection or Object array value returned from a method invocation for evaluation of filters on attributes of Collection objects.
 *
 *
 * @author Hemambara Vamsi Kotari
 */
public class CollectionsAwareFilter extends ComparisonFilter {

    /**
     * Created to support default constructor mechanism
     */
    public CollectionsAwareFilter() {
    }

    /**
     * Takes methodName and convert it to value extractor. Method name should be the name of the method that retrieves {@code Collection} from main object.
     *
     * @param sMethod - methodName
     * @param filter - {@link Filter}
     */
    public CollectionsAwareFilter(String sMethod, Filter filter) {
        super(sMethod, filter);
        this.init(filter);
    }

    /**
     * {@code ValueExtractor} retrieves {@code Collection} from main object.
     *
     * @param extractor - {@link ValueExtractor}
     * @param filter - {@link Filter}
     */
    public CollectionsAwareFilter(ValueExtractor extractor, Filter filter) {
        super(extractor, filter);
        this.init(filter);
    }

    /**
     * Make sure {@link Filter} is NOT NULL. It does not make any sense to parse through collection if filter is null.
     *
     * @param filter
     */
    protected void init(Filter filter){
      if (null == filter) {
        throw new IllegalArgumentException("Filter argument must not be null"); 
      } 
    }


    /**
     * Evaluate the collection, iterate through them and apply filters.
     *
     * @param oExtracted - Extracted collection from main object.
     * @return - True - If any filter pass.
     *          - False - If none of the filter pass.
     */
    @Override
    protected boolean evaluateExtracted(Object oExtracted) {
        Collection aoExtracted = (Collection)oExtracted;
        Filter filter = (Filter) this.getValue();
        for(Object object : aoExtracted){
            if(filter.evaluate(object)){
                return true;
            }
        }
        return false;
    }
}

Here is the usage:

a) First, create the userbean with a person name and list of addresses (like home, office).

b) Then, put the values in coherence cache at line 14.

UserBean userBean1 = new UserBean();
userBean1.setName("Name1");

Address address1 = new Address();
address1.setStreetName("Davidson Drive");
address1.setCity("Charlotte");

Address address2 = new Address();
address2.setStreetName("Bevard st");
address2.setCity("Charlotte");

userBean1.setAddressList(Arrays.asList(address1, address2));

coherenceNamedCache.put(1, userBean1);

c) Apply filters on bean attributes. Line 1-4. We can create N number of filters.

d) Use CollectionsAwareFilter by passing the filters created at #c) and use the bean attribute name of the list.

LikeFilter likeFilter = new LikeFilter("getStreetName","%Drive%", false);
EqualsFilter equalsFilter = new EqualsFilter("getCity","Charlotte");
//... pass N number of filters
AllFilter filter = new AllFilter(new Filter[]{likeFilter, equalsFilter});

// getter name of a list in UserBean
Filter filterCriteria = new CollectionsAwareFilter("getAddressList", filter);

UserBean with a Name and Address as a list of objects:

public class UserBean {
    private String name;
    private List<Address> addressList;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public List<Address> getAddressList() {
        return addressList;
    }

    public void setAddressList(List<Address> addressList) {
        this.addressList = addressList;
    }

    @Override
    public boolean equals(Object o) {
        // write your own way of equals()

    }

    @Override
    public int hashCode() {
        // write your own way of hashCode()
    }
}

AddressBean:

public class Address{
    private String streetName;
    private String city;
    private String country;
    private String zipCode;

    public String getStreetName() {
        return streetName;
    }

    public void setStreetName(String streetName) {
        this.streetName = streetName;
    }

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public String getCountry() {
        return country;
    }

    public void setCountry(String country) {
        this.country = country;
    }

    public String getZipCode() {
        return zipCode;
    }

    public void setZipCode(String zipCode) {
        this.zipCode = zipCode;
    }

    @Override
    public boolean equals(Object o) {
        // write your own way of equals

    }

    @Override
    public int hashCode() {
        // write your own way of hashCode()
    }
}

That's all! Hope you find this helpful.