Refactor and add features to several classes

Several code enhancements were implemented, including the removal of an unused Logger object in LazyStreams class, a simplification in the use of isEmpty() in FlatMapDemo, and the adjustment of lambdas to method references in UsePerson. In addition, a new CompanyEmployee class was created, and a previously commented test was uncommented and fixed in the CompanyEmployeeTest class.

src/main/java/interfaces/CompanyEmployee.java

@@ -0,0 +1,30 @@
+package interfaces;
+
+public class CompanyEmployee implements Company, Employee {
+    private final String first;
+    private final String last;
+
+    public CompanyEmployee(String first, String last) {
+        this.first = first;
+        this.last = last;
+    }
+
+    public String getName() {
+        return Employee.super.getName() + " works for " + Company.super.getName();
+    }
+
+    @Override
+    public String getFirst() {
+        return first;
+    }
+
+    @Override
+    public String getLast() {
+        return last;
+    }
+
+    @Override
+    public void doWork() {
+        System.out.println("Converting caffeine into code for $$$");
+    }
+}

src/main/java/lambdas/UsePerson.java

@@ -1,11 +1,9 @@
 package lambdas;
 
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.LinkedList;
-import java.util.List;
+import java.util.*;
 import java.util.stream.Collectors;
 
+@SuppressWarnings("Convert2MethodRef")
 public class UsePerson {
     public static void main(String[] args) {
         List<String> names = Arrays.asList("John", "Paul", "George", "Ringo");
@@ -49,7 +47,7 @@ public static void main(String[] args) {
         LinkedList<Person> linkedPersons = names.stream()
                 .map(Person::new)
                 .collect(
-                        () -> new LinkedList<Person>(),          // Supplier<LinkedList>
+                        () -> new LinkedList<>(),          // Supplier<LinkedList>
                         (list, person) -> list.add(person),      // BiConsumer<LinkedList, Person>
                         (list1, list2) -> list1.addAll(list2));  // BiConsumer<LinkedList, LinkedList>
         System.out.println(linkedPersons);
@@ -66,5 +64,13 @@ public static void main(String[] args) {
                 .map(Person::new)
                 .collect(Collectors.toCollection(LinkedList::new));
         System.out.println(linkedPersons);
+
+        // Collectors.toMap(keyMapper, valueMapper)
+        Map<String, String> map = fullNames.stream()
+                .map(name -> name.split(" "))
+                .collect(Collectors.toMap(
+                        name -> name[0],  // keyMapper
+                        name -> name[1]));// valueMapper
+        map.forEach((key, value) -> System.out.println(key + " -> " + value));
     }
 }

src/main/java/lazy/LazyStreams.java

@@ -1,11 +1,8 @@
 package lazy;
 
-import java.util.logging.Logger;
 import java.util.stream.IntStream;
 
 public class LazyStreams {
-    private static final Logger logger = Logger.getLogger(LazyStreams.class.getName());
-
     public static int multByTwo(int n) {
         System.out.printf("Inside multByTwo with arg %d on thread %s%n",
                 n, Thread.currentThread().getName());

src/main/java/streams/FlatMapDemo.java

@@ -44,9 +44,8 @@ public static void main(String[] args) {
         //      stream() on an empty collection already returns an empty stream
         customers.stream()
                 .flatMap(customer ->
-                        customer.getOrders().size() == 0 ? Stream.empty() :
+                        customer.getOrders().isEmpty() ? Stream.empty() :
                                 customer.getOrders().stream())
                 .forEach(System.out::println);
-
     }
 }

src/test/java/interfaces/CompanyEmployeeTest.java

@@ -2,6 +2,8 @@
 
 import org.junit.jupiter.api.Test;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 // Create a class called CompanyEmployee that implements both
 //   the Company and Employee interfaces
 // Implement the necessary methods
@@ -11,7 +13,7 @@ public class CompanyEmployeeTest {
 
     @Test
     public void getName() {
-//        CompanyEmployee emp = new CompanyEmployee("Peter", "Gibbons");
-//        assertEquals("Peter Gibbons works for Initech", emp.getName());
+        CompanyEmployee emp = new CompanyEmployee("Peter", "Gibbons");
+        assertEquals("Peter Gibbons works for Initech", emp.getName());
     }
 }