Merge pull request #6461 from rodolforfq/BAEL-2448

BAEL-2448

core-java-collections-list/src/main/java/com/baeldung/collection/filtering/Employee.java

@@ -0,0 +1,44 @@
+package com.baeldung.collection.filtering;
+
+/**
+ * Java 8 Collection Filtering by List of Values base class.
+ *
+ * @author Rodolfo Felipe
+ */
+public class Employee {
+
+    private Integer employeeNumber;
+    private String name;
+    private Integer departmentId;
+
+    public Employee(Integer employeeNumber, String name, Integer departmentId) {
+        this.employeeNumber = employeeNumber;
+        this.name = name;
+        this.departmentId = departmentId;
+    }
+
+    public Integer getEmployeeNumber() {
+        return employeeNumber;
+    }
+
+    public void setEmployeeNumber(Integer employeeNumber) {
+        this.employeeNumber = employeeNumber;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Integer getDepartmentId() {
+        return departmentId;
+    }
+
+    public void setDepartmentId(Integer departmentId) {
+        this.departmentId = departmentId;
+    }
+
+}

core-java-collections-list/src/test/java/com/baeldung/collection/filtering/CollectionFilteringUnitTest.java

@@ -0,0 +1,73 @@
+package com.baeldung.collection.filtering;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import org.hamcrest.Matchers;
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Various filtering examples.
+ *
+ * @author Rodolfo Felipe
+ */
+public class CollectionFilteringUnitTest {
+
+    private List<Employee> buildEmployeeList() {
+        return Arrays.asList(new Employee(1, "Mike", 1), new Employee(2, "John", 1), new Employee(3, "Mary", 1), new Employee(4, "Joe", 2), new Employee(5, "Nicole", 2), new Employee(6, "Alice", 2), new Employee(7, "Bob", 3), new Employee(8, "Scarlett", 3));
+    }
+
+    private List<String> employeeNameFilter() {
+        return Arrays.asList("Alice", "Mike", "Bob");
+    }
+
+    @Test
+    public void givenEmployeeList_andNameFilterList_thenObtainFilteredEmployeeList_usingForEachLoop() {
+        List<Employee> filteredList = new ArrayList<>();
+        List<Employee> originalList = buildEmployeeList();
+        List<String> nameFilter = employeeNameFilter();
+
+        for (Employee employee : originalList) {
+            for (String name : nameFilter) {
+                if (employee.getName()
+                    .equalsIgnoreCase(name)) {
+                    filteredList.add(employee);
+                }
+            }
+        }
+
+        Assert.assertThat(filteredList.size(), Matchers.is(nameFilter.size()));
+    }
+
+    @Test
+    public void givenEmployeeList_andNameFilterList_thenObtainFilteredEmployeeList_usingLambda() {
+        List<Employee> filteredList;
+        List<Employee> originalList = buildEmployeeList();
+        List<String> nameFilter = employeeNameFilter();
+
+        filteredList = originalList.stream()
+            .filter(employee -> nameFilter.contains(employee.getName()))
+            .collect(Collectors.toList());
+
+        Assert.assertThat(filteredList.size(), Matchers.is(nameFilter.size()));
+    }
+
+    @Test
+    public void givenEmployeeList_andNameFilterList_thenObtainFilteredEmployeeList_usingLambdaAndHashSet() {
+        List<Employee> filteredList;
+        List<Employee> originalList = buildEmployeeList();
+        Set<String> nameFilterSet = employeeNameFilter().stream()
+            .collect(Collectors.toSet());
+
+        filteredList = originalList.stream()
+            .filter(employee -> nameFilterSet.contains(employee.getName()))
+            .collect(Collectors.toList());
+
+        Assert.assertThat(filteredList.size(), Matchers.is(nameFilterSet.size()));
+    }
+
+}