BAEL-638 Guava Ordering

guava/src/test/java/org/baeldung/guava/GuavaOrderingTest.java

@@ -0,0 +1,91 @@
+package org.baeldung.guava;
+
+import com.google.common.base.Function;
+import com.google.common.collect.Ordering;
+import com.google.common.primitives.Ints;
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+
+public class GuavaOrderingTest {
+    @Test
+    public void givenListOfIntegers_whenCreateNaturalOrderOrdering_shouldSortProperly() {
+        //given
+        List<Integer> integers = Arrays.asList(3, 2, 1);
+
+        //when
+        integers.sort(Ordering.natural());
+
+        //then
+        assertEquals(Arrays.asList(1, 2, 3), integers);
+    }
+
+    @Test
+    public void givenListOfPersonObject_whenSortedUsingCustomOrdering_shouldSortProperly() {
+        //given
+        List<Person> persons = Arrays.asList(new Person("Michael", 10), new Person("Alice", 3));
+        Ordering<Person> orderingByName = new Ordering<Person>() {
+            @Override
+            public int compare(Person p1, Person p2) {
+                return Ints.compare(p1.age, p2.age);
+            }
+        };
+
+        //when
+        persons.sort(orderingByName);
+
+        //then
+        assertEquals(Arrays.asList(new Person("Alice", 3), new Person("Michael", 10)), persons);
+    }
+
+    @Test
+    public void givenListOfPersonObject_whenSortedUsingChainedOrdering_shouldSortPropely() {
+        //given
+        List<Person> persons = Arrays.asList(new Person("Michael", 10), new Person("Alice", 3), new Person("Thomas", null));
+        Ordering<Person> ordering = Ordering.natural().nullsFirst().onResultOf(new Function<Person, Comparable>() {
+            @Override
+            public Comparable apply(Person person) {
+                return person.age;
+            }
+        });
+
+        //when
+        persons.sort(ordering);
+
+        //then
+        assertEquals(Arrays.asList(new Person("Thomas", null), new Person("Alice", 3), new Person("Michael", 10)), persons);
+    }
+
+
+    class Person {
+        private final String name;
+        private final Integer age;
+
+        private Person(String name, Integer age) {
+            this.name = name;
+            this.age = age;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+
+            Person person = (Person) o;
+
+            if (name != null ? !name.equals(person.name) : person.name != null) return false;
+            return age != null ? age.equals(person.age) : person.age == null;
+
+        }
+
+        @Override
+        public int hashCode() {
+            int result = name != null ? name.hashCode() : 0;
+            result = 31 * result + (age != null ? age.hashCode() : 0);
+            return result;
+        }
+    }
+}