com.github.TKnudsen.ComplexDataObject.model.tools.DataConversion Maven / Gradle / Ivy

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package com.github.TKnudsen.ComplexDataObject.model.tools;

import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Set;

/**
 * 
 * Title: DataConversion
 * 
 *
 * 
 * Description: Provides little helpers for the conversion of general data
 * structures
 * 
 *
 * 
 * Copyright: Copyright (c) 2017
 * 
 *
 * @author Juergen Bernard
 * @version 1.03
 */
public class DataConversion {

	/**
	 * convertss a list of Double objects to an array of double primitives.
	 * 
	 * @param values
	 * @return
	 */
	public static double[] toPrimitives(List values) {
		if (values == null)
			 return null;
				
		return values.stream().mapToDouble(Double::doubleValue).toArray();

		// if (values == null)
		// return null;
		//
		// double[] ret = new double[values.size()];
		//
		// for (int i = 0; i < values.size(); i++)
		// ret[i] = values.get(i).doubleValue();
		//
		// return ret;
	}

	/**
	 * Converts an array of double primitives to an array of Double objects.
	 * 
	 * @param values
	 * @return
	 */
	public static Double[] doublePrimitivesToArray(double[] values) {
		if (values == null)
			return null;
		Double[] array = new Double[values.length];
		for (int i = 0; i < values.length; i++)
			array[i] = values[i];
		return array;
	}

	/**
	 * Converts an array of double primitives to an array of Double objects.
	 * 
	 * @param values
	 * @return
	 */
	public static List doublePrimitivesToList(double[] values) {
		return Arrays.asList(DataConversion.doublePrimitivesToArray(values));
	}

	/**
	 * Converts an array to a List.
	 * 
	 * @param values
	 * @return
	 */
	public static  List arrayToList(T[] values) {
		return new ArrayList(Arrays.asList(values));
	}

	/**
	 * Converts a given Collection to an array.
	 * 
	 * @param collection
	 * @param classType
	 * @return
	 */
	public static  T[] collectionToArray(Collection collection, Class classType) {
		List list = collectionToList(collection);
		return listToArray(list, classType);
	}

	/**
	 * converts a given Collection into a List.
	 * 
	 * @param collection
	 * @return
	 */
	public static  List collectionToList(Collection collection) {
		List list;
		if (collection instanceof List)
			list = (List) collection;
		else
			list = new ArrayList(collection);
		return list;
	}

	/**
	 * Converts a Set into a List.
	 * 
	 * @param set
	 * @return
	 */
	public static  List setToList(Set set) {
		List list = new ArrayList<>();
		list.addAll(set);
		return list;
	}

	/**
	 * abstracts a List of concrete Doubles to Numbers
	 * 
	 * @param values
	 * @return
	 */
	public static List numberListFromDoubleList(List values) {
		List numbers = new ArrayList<>();
		for (Double d : values)
			numbers.add(d);
		return numbers;
	}

	/**
	 * Converts a given List to an array.
	 * 
	 * @param list
	 * @param classType
	 * @return
	 */
	public static  T[] listToArray(List list, Class classType) {
		if (list == null)
			return null;
		if (classType == null)
			throw new IllegalArgumentException("DataConversion.listToArray: class information missing.");

		@SuppressWarnings("unchecked")
		T[] array = (T[]) Array.newInstance(classType, list.size());

		for (int i = 0; i < list.size(); ++i) {
			array[i] = list.get(i);
		}

		return array;
	}
}