Added Selection Sort custom implementation

Created algorithm to get the cheapest value

Created 'Product' as a representation model

Extract algorithm to getCheapest method

Created method 'sortingByCheapest' using getCheapest method

Clone original array to prevents its modification

Move test to specific class

Author: zevolution

src/main/java/br/com/zevolution/algorithms/sorting/selectionsort/Product.java

@@ -0,0 +1,22 @@
+package br.com.zevolution.algorithms.sorting.selectionsort;
+
+public class Product {
+	
+	private String description;
+	private double price;
+	
+	public Product(String description, double price) {
+		this.description = description;
+		this.price = price;
+	}
+
+	public double getPrice() {
+		return price;
+	}
+	
+	@Override
+	public String toString() {
+		return this.description;
+	}
+	
+}

src/main/java/br/com/zevolution/algorithms/sorting/selectionsort/SelectionSort.java

@@ -0,0 +1,28 @@
+package br.com.zevolution.algorithms.sorting.selectionsort;
+
+public class SelectionSort {
+	
+	public static Product[] sortingByCheapest(Product[] products, int length) {
+		Product[] array = products.clone();
+		for (int current = 0; current < length - 1; current++) {
+			int cheapest = getCheapest(array, current, length - 1);
+
+			Product currentProduct = array[current];
+			Product cheapestProduct = array[cheapest];
+
+			array[current] = cheapestProduct;
+			array[cheapest] = currentProduct;
+		}
+		return array;
+	}
+
+	private static int getCheapest(Product[] products, int beginIndex, int endIndex) {
+		int cheapest = beginIndex;
+		for (int current = beginIndex; current <= endIndex; current++) {
+			if (products[current].getPrice() < products[cheapest].getPrice()) {
+				cheapest = current;
+			}		
+		}
+		return cheapest;
+	}
+}

src/test/java/br/com/zevolution/algorithms/sorting/selectionsort/SelectionSortTest.java

@@ -0,0 +1,39 @@
+package br.com.zevolution.algorithms.sorting.selectionsort;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+import org.junit.Before;
+
+public class SelectionSortTest {
+
+	private static final double CHEAPEST_PRODUCT = 5;
+	private static final double MOST_EXPENSIVE_PRODUCT = 50;
+	private Product[] products;
+
+	@Before
+	public void init() {
+		Product[] array = {
+				new Product("iMac", MOST_EXPENSIVE_PRODUCT),
+				new Product("iPhone", 8),
+				new Product("Notebook", 7),
+				new Product("Keyboard", 9),
+				new Product("Mouse", CHEAPEST_PRODUCT)
+		};
+		this.products = array;
+	}
+
+	@Test
+	public void should_Get_CheapestProduct() {
+		Product[] ordened = SelectionSort.sortingByCheapest(this.products, this.products.length);
+		assertEquals(CHEAPEST_PRODUCT, ordened[0].getPrice(), 0);
+	}
+
+	@Test
+	public void should_Get_MostExpensiveProduct() {
+		Product[] ordened = SelectionSort.sortingByCheapest(this.products, this.products.length);
+		assertEquals(MOST_EXPENSIVE_PRODUCT, ordened[ordened.length - 1].getPrice(), 0);
+	}
+
+}