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package com.github.napp.util.mass;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import com.github.napp.util.UString;
import com.github.napp.util.mass.InternalEvaluator.EvaluationResult;
import com.github.napp.util.mass.InternalEvaluator.IDupeChecker;
/**
* @author Alexandru Bledea
* @since Jul 30, 2013
*/
public class CollectionUtil {
/**
* Used to transform an array of objects into a collection
* The values for the second collection are generated by using a evaluator.
* Objects are null or that evaluate to null will be skipped
* @param objects the collection from which we create the collection
* @param evaluator the evaluator
* @param collection the collection where the evaluation result will be added
* @return the collection passed as argument filled with the evaluated values, if an object evaluates to null, it is not added to the collection
*/
public static , V, O> C createCollection(O[] objects, IEvaluator evaluator, C collection) {
if (objects == null) {
return collection;
}
return createCollection(Arrays.asList(objects), evaluator, collection);
}
/**
* Used to transform a collection of objects into another collection
* The values for the second collection are generated by using a evaluator.
* Objects are null or that evaluate to null will be skipped
* @param objects the collection from which we create the collection
* @param evaluator the evaluator
* @param collection the collection where the evaluation result will be added
* @return the collection passed as argument filled with the evaluated values, if an object evaluates to null, it is not added to the collection
*/
public static , V, O> C createCollection(Collection objects, IEvaluator evaluator, C collection) {
try {
return createCollection(objects, evaluator, collection, true);
} catch (DuplicateKeyException e) {
return null; //not going to happen
}
}
/**
* Used to transform a collection of objects into another collection
* The values for the second collection are generated by using a evaluator.
* Use allowDupes if you want values that evaluate to the same object to be added to the collection.
* Objects are null or that evaluate to null will be skipped
* @param objects the collection from which we create the collection
* @param evaluator the evaluator
* @param collection the collection where the evaluation result will be added
* @param allowDupes if we allow dupes in the collection
* @return the collection passed as argument filled with the evaluated values, if an object evaluates to null, it is not added to the collection
* @throws DuplicateKeyException if we have a duplicate key and we don't allow that
*/
public static , V, O> C createCollection(Collection objects, IEvaluator evaluator, C collection,
boolean allowDupes) throws DuplicateKeyException {
return createCollection(objects, evaluator, collection, allowDupes, true);
}
/**
* Used to transform a collection of objects into another collection
* The values for the second collection are generated by using a evaluator.
* Use allowDupes if you want values that evaluate to the same object to be added to the collection.
* Use skipNullObjects to avoid {@link java.lang.NullPointerException} if a null value is in the collection
* Objects that evaluate to null will be skipped
* @param objects the collection from which we create the collection
* @param evaluator the evaluator
* @param collection the collection where the evaluation result will be added
* @param allowDupes if we allow dupes in the collection
* @param skipNullObjects if we skip null objects, if we don't we will get a we will get a {@link java.lang.NullPointerException}
* @return the collection passed as argument filled with the evaluated values, if an object evaluates to null, it is not added to the collection
* @throws DuplicateKeyException if we have a duplicate key and we don't allow that
* @throws NullPointerException if there is a null value in the collection and we don't skip it
*/
public static , V, O> C createCollection(Collection objects, IEvaluator evaluator, C collection,
boolean allowDupes, boolean skipNullObjects) throws DuplicateKeyException {
return createCollection(objects, evaluator, collection, allowDupes, skipNullObjects, true);
}
/**
* Used to transform a collection of objects into another collection
* The values for the second collection are generated by using a evaluator.
* Use allowDupes if you want values that evaluate to the same key to be added to the collection.
* Use skipNullObjects to avoid {@link java.lang.NullPointerException} if a null value is in the collection
* Use skipNullValues to skip adding object to the map it evaluates to null
* @param objects the collection from which we create the collection
* @param evaluator the evaluator
* @param collection the collection where the evaluation result will be added
* @param allowDupes if we allow dupes in the collection
* @param skipNullObjects if we skip null objects, if we don't we will get a we will get a {@link java.lang.NullPointerException}
* @param skipNullValues if we want to skip the null values from being added to the collection
* @return the collection passed as argument filled with the evaluated values
* @throws DuplicateKeyException if we have a duplicate key and we don't allow that
* @throws NullPointerException if there is a null value in the collection and we don't skip it
*/
public static , V, O> C createCollection(Collection objects, IEvaluator evaluator, final C collection,
boolean allowDupes, boolean skipNullObjects, boolean skipNullValues) throws DuplicateKeyException {
if (objects == null) {
objects = new ArrayList();
}
EvaluationResult result = new EvaluationResult();
IDupeChecker dupeChecker = new IDupeChecker() {
@Override
public boolean checkIfDupe(V what) {
return collection.contains(what);
}
};
for (O t : objects) {
result = InternalEvaluator.evaluate(t, skipNullObjects, evaluator, skipNullValues, allowDupes, dupeChecker, result);
if (!result.skip()) {
collection.add(result.getResult());
}
}
return collection;
}
/**
* used to break a large collection into smaller collection
* @param collection
* @param maxElements
* @param clazz
* @return
*/
public static List> breakCollection(Collection collection, int maxElements, Class clazz) {
List> result = new ArrayList>();
C step = instantiate(clazz);
Iterator iterator = collection.iterator();
while (iterator.hasNext()) {
if (step.size() == maxElements) {
result.add(step);
step = instantiate(clazz);
}
step.add(iterator.next());
}
if (!step.isEmpty()) {
result.add(step);
}
return result;
}
/**
* @param collection
* @param evaluator
* @param emptyMessage
* @return
*/
public static String join(Collection collection, IStringEvaluator evaluator, String separator, String emptyMessage) {
List strings = new ArrayList();
createCollection(collection, evaluator, strings);
Iterator iterator = strings.iterator();
if (iterator.hasNext()) {
return UString.join(iterator, separator);
}
return emptyMessage;
}
/**
* @param collection
* @param evaluator
* @return an empty string if no values
*/
public static String join(Collection collection, IStringEvaluator evaluator, String separator) {
return join(collection, evaluator, separator, "");
}
/**
* @param element
* @param collection
*/
public static void addIfNotNull(O element, Collection collection) {
if (element != null) {
collection.add(element);
}
}
/**
* @param clazz
* @return
*/
public static C instantiate(Class clazz) {
try {
return clazz.newInstance();
} catch (Exception e) {
throw new RuntimeException("Illegal implementation class " + clazz.getName());
}
}
}
