Adding java 8 features code

Author: Saurabh Oza

java-8-features/pom.xml

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+<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/maven-v4_0_0.xsd">
+ <modelVersion>4.0.0</modelVersion>
+ <groupId>com.onlyfullstack</groupId>
+ <artifactId>java-8-features</artifactId>
+ <packaging>jar</packaging>
+ <version>1.0-SNAPSHOT</version>
+ <name>java-8-features</name>
+ <url>http://maven.apache.org</url>
+ <dependencies>
+ <dependency>
+ <groupId>junit</groupId>
+ <artifactId>junit</artifactId>
+ <version>3.8.1</version>
+ <scope>test</scope>
+ </dependency>
+ </dependencies>
+</project>

java-8-features/src/main/java/com/onlyfullstack/bean/GraphicsCard.java

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+package com.onlyfullstack.bean;
+
+public class GraphicsCard {
+
+private String size;
+private GraphicsMemory graphicsMemory;
+
+
+public GraphicsCard(String size, GraphicsMemory graphicsMemory) {
+super();
+this.size = size;
+this.graphicsMemory = graphicsMemory;
+}
+
+public GraphicsMemory getGraphicsMemory() {
+return graphicsMemory;
+}
+
+public void setGraphicsMemory(GraphicsMemory graphicsMemory) {
+this.graphicsMemory = graphicsMemory;
+}
+
+public GraphicsCard() {
+super();
+}
+
+public String getSize() {
+return size;
+}
+
+public void setSize(String size) {
+this.size = size;
+}
+
+@Override
+public String toString() {
+return "GraphicsCard [size=" + size + "]";
+}
+
+}

java-8-features/src/main/java/com/onlyfullstack/bean/GraphicsMemory.java

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+package com.onlyfullstack.bean;
+
+public class GraphicsMemory {
+
+private String dedicatedMemory;
+private String memoryType;
+
+public GraphicsMemory(String dedicatedMemory, String memoryType) {
+super();
+this.dedicatedMemory = dedicatedMemory;
+this.memoryType = memoryType;
+}
+
+public String getDedicatedMemory() {
+return dedicatedMemory;
+}
+
+public void setDedicatedMemory(String dedicatedMemory) {
+this.dedicatedMemory = dedicatedMemory;
+}
+
+public String getMemoryType() {
+return memoryType;
+}
+
+public void setMemoryType(String memoryType) {
+this.memoryType = memoryType;
+}
+}

java-8-features/src/main/java/com/onlyfullstack/bean/SmartPhone.java

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+package com.onlyfullstack.bean;
+
+import java.util.Optional;
+
+public class SmartPhone {
+
+private Optional<GraphicsCard> graphicsCard;
+
+public Optional<GraphicsCard> getGraphicsCard() {
+return graphicsCard;
+}
+public void setGraphicsCard(Optional<GraphicsCard> graphicsCard) {
+this.graphicsCard = graphicsCard;
+}
+@Override
+public String toString() {
+return "SmartPhone [graphicsCard=" + graphicsCard
++ "]";
+}
+
+
+}

java-8-features/src/main/java/com/onlyfullstack/bean/Student.java

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+package com.onlyfullstack.bean;
+
+public class Student {
+
+private String name;
+private String city;
+private int age;
+private String[] courses;
+
+public Student(String name, String city, int age, String[] courses) {
+super();
+this.name = name;
+this.city = city;
+this.age = age;
+this.courses = courses;
+}
+public String[] getCourses() {
+return courses;
+}
+public void setCourses(String[] courses) {
+this.courses = courses;
+}
+public int getAge() {
+return age;
+}
+public void setAge(int age) {
+this.age = age;
+}
+public String getName() {
+return name;
+}
+public void setName(String name) {
+this.name = name;
+}
+public String getCity() {
+return city;
+}
+public void setCity(String city) {
+this.city = city;
+}
+
+@Override
+public String toString() {
+return "Student [name=" + name + ", city=" + city + ", age=" + age + "]";
+}
+}

java-8-features/src/main/java/com/onlyfullstack/lambdas/IConnection.java

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+package com.onlyfullstack.lambdas;
+
+@FunctionalInterface
+public interface IConnection {
+
+public void connect();
+
+default void print() {
+System.out.println("in default print method");
+}
+
+static void description() {
+System.out.println("in static method");
+}
+}

java-8-features/src/main/java/com/onlyfullstack/lambdas/Lambda.java

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+package com.onlyfullstack.lambdas;
+
+public class Lambda {
+
+public static void main(String[] args) {
+IConnection connection = () -> {System.out.println("Implementing the connect method");};
+
+connection.connect();
+connection.print();
+IConnection.description();
+simpleConceptWithRunnable();
+}
+
+private static void simpleConceptWithRunnable() {
+Runnable runnable = new Runnable() { // boilerplate code which needs to be written everytime
+@Override
+public void run() {
+System.out.println("Inside annonymos inner class");
+}
+};
+
+Runnable runnable2 = () -> { // Lambda expression
+System.out.println("Inside lambda expression");
+};
+
+Thread thread = new Thread(runnable);
+thread.start();
+
+thread = new Thread(runnable2);
+thread.start();
+
+SingleParam singleParam = (param) -> {System.out.printf("Hello %s\n",param);};
+singleParam.print("saurabh");
+
+DoubleParam doubleParam = (param1, param2) -> System.out.printf("param1 : %s, param2: %s\n", param1, param2);
+doubleParam.print("OnlyFullstack", "Development");
+}
+
+interface SingleParam {
+public void print(String param);
+}
+
+interface DoubleParam {
+public void print(String param1, String param2);
+}
+}

java-8-features/src/main/java/com/onlyfullstack/lambdas/MethodReference.java

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+package com.onlyfullstack.lambdas;
+
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import com.onlyfullstack.bean.Student;
+import com.onlyfullstack.util.JavaInputFixture;
+
+public class MethodReference {
+
+public static void main(String[] args) {
+staticReference_WithoutMethodRef();
+staticReference_WithMethodRef();
+
+instanceReferenceWithClass_WithMethodRef();
+instanceReferenceWithClass_WithoutMethodRef();
+
+instanceReference_WithoutMethodRef();
+instanceReference_WithMethodRef();
+}
+
+private static void printMe(Integer input) {
+System.out.println("Printing "+ input);
+}
+
+private static void staticReference_WithoutMethodRef() {
+Stream<Integer> stream = Stream.of(1,2,3,4,5,6,7,8,9);
+stream.filter(i -> i%2==0 )
+.forEach(i -> MethodReference.printMe(i));
+}
+
+private static void staticReference_WithMethodRef() {
+Stream<Integer> stream = Stream.of(1,2,3,4,5,6,7,8,9);
+stream.filter(i -> i%2==0 )
+.forEach(MethodReference::printMe);
+}
+
+private static void instanceReference_WithoutMethodRef() {
+Stream<Integer> stream = Stream.of(1,2,3,4,5,6,7,8,9);
+stream.filter(i -> i%2==0 )
+.forEach((i -> System.out.println(i)));
+}
+
+private static void instanceReference_WithMethodRef() {
+Stream<Integer> stream = Stream.of(1,2,3,4,5,6,7,8,9);
+stream.filter(i -> i%2==0 )
+.forEach(System.out::println);
+}
+
+private static void instanceReferenceWithClass_WithoutMethodRef() {
+List<Student> students = JavaInputFixture.createList();
+Set<String> names = students.stream()
+.map(student -> student.getName()) // this will convert the Student Stream into String Stream by 
+ // applying the getName()
+.collect(Collectors.toSet());
+
+System.out.printf("Names of all students %s\n", names);
+}
+
+private static void instanceReferenceWithClass_WithMethodRef() {
+List<Student> students = JavaInputFixture.createList();
+Set<String> names = students.stream()
+.map(Student::getName) // this will convert the Student Stream into String Stream by 
+ // applying the getName()
+.collect(Collectors.toSet());
+
+System.out.printf("Names of all students %s\n", names);
+}
+}

java-8-features/src/main/java/com/onlyfullstack/optional/OptionalFeature.java

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+package com.onlyfullstack.optional;
+
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.LinkedHashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Optional;
+import java.util.PriorityQueue;
+
+import com.onlyfullstack.bean.GraphicsCard;
+import com.onlyfullstack.bean.GraphicsMemory;
+import com.onlyfullstack.bean.SmartPhone;
+
+public class OptionalFeature {
+
+public static void main(String[] args) {
+getGraphicsCardSize(createSmartPhoneWithGraphicsCard());
+getGraphicsCardSize(createSmartPhoneWithoutGraphicsCard());
+getGraphicsCardSize(createSmartPhoneWithEmptyGraphicsCard());
+}
+
+private static void getGraphicsCardSize(SmartPhone smartPhone) {
+String size = smartPhone.getGraphicsCard() 
+ .map(GraphicsCard::getGraphicsMemory) // map returns the Optional of type passed as a parameter (here its string)
+ .map(GraphicsMemory::getDedicatedMemory)
+ .orElse("unkonwn");
+System.out.println("Size : " + size + ", for Object : "+smartPhone.toString());
+}
+
+private static void ofVsOfNullable() {
+Optional<GraphicsCard> graphicsCard = Optional.of(new GraphicsCard());
+if(graphicsCard.isPresent()) {
+System.out.println(graphicsCard.get());
+}
+
+graphicsCard.ifPresent(System.out::println);
+GraphicsCard newCard = graphicsCard.get();
+}
+
+private static SmartPhone createSmartPhoneWithGraphicsCard() {
+SmartPhone smartPhone = new SmartPhone();
+GraphicsMemory memory = new GraphicsMemory("4 GB", "");
+Optional<GraphicsCard> card = Optional.ofNullable(new GraphicsCard("4 gb", memory));
+smartPhone.setGraphicsCard(card);
+return smartPhone;
+}
+
+private static SmartPhone createSmartPhoneWithoutGraphicsCard() {
+SmartPhone smartPhone = new SmartPhone();
+Optional<GraphicsCard> card = Optional.ofNullable(null);
+smartPhone.setGraphicsCard(card);
+return smartPhone;
+}
+
+private static SmartPhone createSmartPhoneWithEmptyGraphicsCard() {
+SmartPhone smartPhone = new SmartPhone();
+Optional<GraphicsCard> card = Optional.ofNullable(new GraphicsCard());
+smartPhone.setGraphicsCard(card);
+return smartPhone;
+}
+
+private static void traditionalApproach(SmartPhone smartPhone) {
+String size = "unknown";
+if(smartPhone.getGraphicsCard()!=null) {
+GraphicsCard graphicsCard = smartPhone.getGraphicsCard().get();
+if(graphicsCard != null) {
+GraphicsMemory graphicsMemory = graphicsCard.getGraphicsMemory();
+if(graphicsMemory != null && graphicsMemory.getDedicatedMemory() != null) {
+size = graphicsMemory.getDedicatedMemory();
+}
+}
+}
+System.out.println("Size : " + size + ", for Object : "+smartPhone.toString());
+}
+}