BAEL-2324 sorting arrays

core-java-arrays/src/test/java/com/baeldung/sort/ArraySortUnitTest.java

@@ -0,0 +1,118 @@
+package com.baeldung.sort;
+
+import com.baeldung.arraycopy.model.Employee;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.stream.IntStream;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+
+public class ArraySortUnitTest {
+    private Employee[] employees;
+    private int[] numbers;
+    private String[] strings;
+
+    @Before
+    public void setup() {
+        createEmployeesArray();
+        createNumbersArray();
+        createStringArray();
+    }
+
+    private void createEmployeesArray() {
+        employees = new Employee[5];
+        Employee employee;
+        for (int i = 1; i <= employees.length; i++) {
+            employee = new Employee(i, "Emp" + i);
+            employees[i - 1] = employee;
+        }
+        Collections.shuffle(Arrays.asList(employees));
+    }
+
+    private void createNumbersArray() {
+        numbers = new int[]{-8, 7, 5, 9, 10, -2, 3};
+    }
+
+    private void createStringArray() {
+        strings = new String[]{"learning", "java", "with", "baeldung"};
+    }
+
+    @Test
+    public void givenIntArray_whenSortingAscending_thenCorrectlySorted() {
+        Arrays.sort(numbers);
+
+        assertArrayEquals(new int[]{-8, -2, 3, 5, 7, 9, 10}, numbers);
+    }
+
+    @Test
+    public void givenIntArray_whenSortingDescending_thenCorrectlySorted() {
+        numbers = IntStream.of(numbers).boxed().sorted(Comparator.reverseOrder()).mapToInt(i -> i).toArray();
+
+        assertArrayEquals(new int[]{10, 9, 7, 5, 3, -2, -8}, numbers);
+    }
+
+    @Test
+    public void givenStringArray_whenSortingAscending_thenCorrectlySorted() {
+        Arrays.sort(strings);
+
+        assertArrayEquals(new String[]{"baeldung", "java", "learning", "with"}, strings);
+    }
+
+    @Test
+    public void givenStringArray_whenSortingDescending_thenCorrectlySorted() {
+        Arrays.sort(strings, Comparator.reverseOrder());
+
+        assertArrayEquals(new String[]{"with", "learning", "java", "baeldung"}, strings);
+    }
+
+    @Test
+    public void givenObjectArray_whenSortingAscending_thenCorrectlySorted() {
+        Arrays.sort(employees, Comparator.comparing(Employee::getName));
+
+        Employee[] sorted = new Employee[]{
+          new Employee(1, "Emp1"),
+          new Employee(2, "Emp2"),
+          new Employee(3, "Emp3"),
+          new Employee(4, "Emp4"),
+          new Employee(5, "Emp5")
+        };
+
+        assertEquals(sorted[0].getId(), employees[0].getId());
+    }
+
+    @Test
+    public void givenObjectArray_whenSortingDescending_thenCorrectlySorted() {
+        Arrays.sort(employees, Comparator.comparing(Employee::getName).reversed());
+
+        Employee[] sorted = new Employee[]{
+          new Employee(5, "Emp5"),
+          new Employee(4, "Emp4"),
+          new Employee(3, "Emp3"),
+          new Employee(2, "Emp2"),
+          new Employee(1, "Emp1")
+        };
+
+        assertEquals(sorted[0].getId(), employees[0].getId());
+    }
+
+    @Test
+    public void givenObjectArray_whenSortingMultipleAttributesAscending_thenCorrectlySorted() {
+        Arrays.sort(employees, Comparator.comparing(Employee::getName).thenComparing(Employee::getId));
+
+        Employee[] sorted = new Employee[]{
+          new Employee(1, "Emp1"),
+          new Employee(2, "Emp2"),
+          new Employee(3, "Emp3"),
+          new Employee(4, "Emp4"),
+          new Employee(5, "Emp5")
+        };
+
+        assertEquals(sorted[0].getId(), employees[0].getId());
+    }
+
+}