java-8 optional and inheritance

Author: arpitaggarwal

pom.xml

@@ -1,6 +1,26 @@
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-  <modelVersion>4.0.0</modelVersion>
-  <groupId>com.test</groupId>
-  <artifactId>java-8</artifactId>
-  <version>0.0.1-SNAPSHOT</version>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<groupId>com.test</groupId>
+	<artifactId>java-8</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<dependencies>
+		<dependency>
+			<groupId>junit</groupId>
+			<artifactId>junit</artifactId>
+			<version>4.12</version>
+		</dependency>
+		<dependency>
+			<groupId>org.hamcrest</groupId>
+			<artifactId>hamcrest-core</artifactId>
+			<version>1.3</version>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.hamcrest</groupId>
+			<artifactId>hamcrest-library</artifactId>
+			<version>1.3</version>
+			<scope>test</scope>
+		</dependency>
+	</dependencies>
 </project>

src/main/java/com/test/inheritance/ABC.java

@@ -0,0 +1,14 @@
+package com.test.inheritance;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public interface ABC<T, D, K, V> {
+
+	default List<String> getSrc(DEF def, XYZ xyz) {
+		final List<String> defaultList = new ArrayList<>();
+		defaultList.add("default");
+		defaultList.add("another-default");
+		return defaultList;
+	}
+}

src/main/java/com/test/inheritance/ABCImpl.java

@@ -0,0 +1,12 @@
+package com.test.inheritance;
+
+import java.util.List;
+
+public class ABCImpl implements ABC<String, Integer, String, Integer> {
+
+	public List<String> getSrcImpl(DEF def, XYZ xyz) {
+		final List<String> list = getSrc(def, xyz);
+		list.add("implementation");
+		return list;
+	}
+}

src/main/java/com/test/inheritance/DEF.java

@@ -0,0 +1,5 @@
+package com.test.inheritance;
+
+public class DEF {
+
+}

src/main/java/com/test/inheritance/XYZ.java

@@ -0,0 +1,5 @@
+package com.test.inheritance;
+
+public class XYZ {
+
+}

src/main/java/com/test/optional/OptionalExample.java

@@ -0,0 +1,26 @@
+package com.test.optional;
+
+import java.util.Optional;
+
+public class OptionalExample {
+
+	public static void main(String[] args) {
+
+		Optional<String> emptyOptional = Optional.empty();
+		System.out.println(emptyOptional);
+
+		String val = emptyOptional.orElse("default-value");
+		System.out.println(val);
+
+		Optional<String> optional = Optional.of("hello");
+		System.out.println(optional.get() + " Or Else :: "
+				+ optional.orElse("hello-world"));
+
+		optional.ifPresent( System.out::println );
+
+		
+		Optional<String> optionalOfNullable = Optional.ofNullable(null);
+		System.out.println(optionalOfNullable.isPresent());
+
+	}
+}

src/test/java/com/test/inheritance/ABCImplTest.java

@@ -0,0 +1,37 @@
+package com.test.inheritance;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.empty;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.not;
+import static org.hamcrest.Matchers.contains;
+import java.util.Collection;
+import java.util.List;
+
+import org.junit.Before;
+import org.junit.Test;
+
+public class ABCImplTest {
+
+	private ABCImpl abcImpl;
+
+	@Before
+	public void setup() {
+		abcImpl = new ABCImpl();
+	}
+
+	@Test
+	public void testGetSrc() throws Exception {
+		List<String> result = abcImpl.getSrc(new DEF(), new XYZ());
+		assertThat((Collection<String>) result, is(not(empty())));
+		assertThat(result, contains("default", "another-default"));
+	}
+	
+
+	@Test
+	public void testABCImplGetSrc() throws Exception {
+		List<String> result = abcImpl.getSrcImpl(new DEF(), new XYZ());
+		assertThat((Collection<String>) result, is(not(empty())));
+		assertThat(result, contains("default", "another-default", "implementation"));
+	}
+}