optional orelse optional ex

lor6 · lor6 · commit ca9f1bbc4262 · 2018-05-27T15:42:59.000+03:00
diff --git a/core-java-9/pom.xml b/core-java-9/pom.xml
@@ -47,6 +47,11 @@
             <version>${awaitility.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -89,6 +94,7 @@
         <awaitility.version>1.7.0</awaitility.version>
         <maven.compiler.source>1.9</maven.compiler.source>
         <maven.compiler.target>1.9</maven.compiler.target>
+        <guava.version>25.1-jre</guava.version>
     </properties>
 
 </project>
diff --git a/core-java-9/src/main/java/com/baeldung/optionals/Optionals.java b/core-java-9/src/main/java/com/baeldung/optionals/Optionals.java
@@ -0,0 +1,26 @@
+package com.baeldung.optionals;
+
+import java.util.Optional;
+
+public class Optionals {
+
+    public static <T> Optional<T> or(Optional<T> optional, Optional<T> fallback) {
+        return optional.isPresent() ? optional : fallback;
+    }
+
+    public static Optional<String> getName(Optional<String> name) {
+        return name.or(() -> getCustomMessage());
+    }
+
+    public static com.google.common.base.Optional<String> getOptionalGuavaName(com.google.common.base.Optional<String> name) {
+        return name.or(getCustomMessageGuava());
+    }
+
+    private static Optional<String> getCustomMessage() {
+        return Optional.of("Name not provided");
+    }
+
+    private static com.google.common.base.Optional<String> getCustomMessageGuava() {
+        return com.google.common.base.Optional.of("Name not provided");
+    }
+} 
diff --git a/core-java-9/src/test/java/com/baeldung/optionals/OptionalsTest.java b/core-java-9/src/test/java/com/baeldung/optionals/OptionalsTest.java
@@ -0,0 +1,51 @@
+package com.baeldung.optionals;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Optional;
+
+import org.junit.Test;
+
+public class OptionalsTest {
+
+    @Test
+    public void givenOptional_whenEmptyValue_thenCustomMessage() {
+        assertEquals(Optional.of("Name not provided"), Optionals.getName(Optional.ofNullable(null)));
+    }
+
+    @Test
+    public void givenOptional_whenValue_thenOptional() {
+        String name = "Filan Fisteku";
+        Optional<String> optionalString = Optional.ofNullable(name);
+        assertEquals(optionalString, Optionals.getName(optionalString));
+    }
+    
+    @Test
+    public void givenOptional_whenValue_thenOptionalGeneralMethod() {
+        String name = "Filan Fisteku";
+        String missingOptional = "Name not provided";
+        Optional<String> optionalString = Optional.ofNullable(name);
+        Optional<String> fallbackOptionalString = Optional.ofNullable(missingOptional);
+        assertEquals(optionalString, Optionals.or(optionalString, fallbackOptionalString));
+    }
+    
+    @Test
+    public void givenEmptyOptional_whenValue_thenOptionalGeneralMethod() {
+        String missingOptional = "Name not provided";
+        Optional<String> optionalString = Optional.empty();
+        Optional<String> fallbackOptionalString = Optional.ofNullable(missingOptional);
+        assertEquals(fallbackOptionalString, Optionals.or(optionalString, fallbackOptionalString));
+    }
+
+    @Test
+    public void givenGuavaOptional_whenInvoke_thenOptional() {
+        String name = "Filan Fisteku";
+        com.google.common.base.Optional<String> stringOptional = com.google.common.base.Optional.of(name);
+        assertEquals(stringOptional, Optionals.getOptionalGuavaName(stringOptional));
+    }
+
+    @Test
+    public void givenGuavaOptional_whenNull_thenDefaultText() {
+        assertEquals(com.google.common.base.Optional.of("Name not provided"), Optionals.getOptionalGuavaName(com.google.common.base.Optional.fromNullable(null)));
+    }
+} 
