BAEL-5558: Sorting By Date in Java (#12132)

* [BAEL-5438] Added Criteria Queries for Employee

* [BAEL-5558] Sorting By Date in Java

* BAEL-5558: Added and refactored tests name

* [BAEL-5558] Refactored the code.

* [BAEL-5558] Resolved PMD violation.

Co-authored-by: Mayank Agarwal <mayankaggarwal@zeta.tech>

core-java-modules/core-java-collections-4/pom.xml

@@ -14,4 +14,12 @@
         <version>0.0.1-SNAPSHOT</version>
     </parent>
 
+    <dependencies>
+        <dependency>
+            <groupId>commons-lang</groupId>
+            <artifactId>commons-lang</artifactId>
+            <version>2.2</version>
+        </dependency>
+    </dependencies>
+
 </project>

core-java-modules/core-java-collections-4/src/main/java/com/baeldung/collections/sorting/Employee.java

@@ -0,0 +1,72 @@
+package com.baeldung.collections.sorting;
+
+import java.util.Date;
+
+public class Employee implements Comparable<Employee>{
+
+  private String name;
+  private int age;
+  private double salary;
+  private Date joiningDate;
+
+  public Employee(String name, int age, double salary, Date joiningDate) {
+    this.name = name;
+    this.age = age;
+    this.salary = salary;
+    this.joiningDate = joiningDate;
+  }
+
+  public String getName() {
+    return name;
+  }
+
+  public void setName(String name) {
+    this.name = name;
+  }
+
+  public int getAge() {
+    return age;
+  }
+
+  public void setAge(int age) {
+    this.age = age;
+  }
+
+  public double getSalary() {
+    return salary;
+  }
+
+  public void setSalary(double salary) {
+    this.salary = salary;
+  }
+
+  public Date getJoiningDate() {
+    return joiningDate;
+  }
+
+  public void setJoiningDate(Date joiningDate) {
+    this.joiningDate = joiningDate;
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    return ((Employee) obj).getName()
+      .equals(getName());
+  }
+
+  @Override
+  public String toString() {
+    return new StringBuffer().append("(")
+      .append(getName()).append(",")
+      .append(getAge())
+      .append(",")
+      .append(getSalary()).append(",").append(getJoiningDate())
+      .append(")")
+      .toString();
+  }
+
+  @Override
+  public int compareTo(Employee employee) {
+    return getJoiningDate().compareTo(employee.getJoiningDate());
+  }
+}

core-java-modules/core-java-collections-4/src/test/java/com/baeldung/collections/sorting/EmployeeSortingByDateUnitTest.java

@@ -0,0 +1,146 @@
+package com.baeldung.collections.sorting;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.Date;
+import java.util.List;
+import org.apache.commons.lang.time.DateUtils;
+import org.junit.Before;
+import org.junit.Test;
+
+public class EmployeeSortingByDateUnitTest {
+
+  private List<Employee> employees = new ArrayList<>();
+  private List<Employee> employeesSortedByDateAsc = new ArrayList<>();
+  private List<Employee> employeesSortedByDateDesc = new ArrayList<>();
+
+  @Before
+  public void initVariables() {
+
+    Collections.addAll(employees,
+      new Employee("Earl", 43, 10000, DateUtils.addMonths(new Date(), -2)),
+      new Employee("Frank", 33, 7000, DateUtils.addDays(new Date(), -20)),
+      new Employee("Steve", 26, 6000, DateUtils.addDays(new Date(), -10)),
+      new Employee("Jessica", 23, 4000, DateUtils.addMonths(new Date(), -6)),
+      new Employee("Pearl", 33, 6000, DateUtils.addYears(new Date(), -1)),
+      new Employee("John", 23, 5000, new Date())
+    );
+
+    Collections.addAll(employeesSortedByDateDesc,
+      new Employee("John", 23, 5000, new Date()),
+      new Employee("Steve", 26, 6000, DateUtils.addDays(new Date(), -10)),
+      new Employee("Frank", 33, 7000, DateUtils.addDays(new Date(), -20)),
+      new Employee("Earl", 43, 10000, DateUtils.addMonths(new Date(), -2)),
+      new Employee("Jessica", 23, 4000, DateUtils.addMonths(new Date(), -6)),
+      new Employee("Pearl", 33, 6000, DateUtils.addYears(new Date(), -1))
+    );
+
+    Collections.addAll(employeesSortedByDateAsc,
+      new Employee("Pearl", 33, 6000, DateUtils.addYears(new Date(), -1)),
+      new Employee("Jessica", 23, 4000, DateUtils.addMonths(new Date(), -6)),
+      new Employee("Earl", 43, 10000, DateUtils.addMonths(new Date(), -2)),
+      new Employee("Frank", 33, 7000, DateUtils.addDays(new Date(), -20)),
+      new Employee("Steve", 26, 6000, DateUtils.addDays(new Date(), -10)),
+      new Employee("John", 23, 5000, new Date())
+    );
+  }
+
+  @Test
+  public void givenEmpList_SortEmpList_thenSortedListinNaturalOrder() {
+    Collections.sort(employees);
+
+    assertEquals(employees, employeesSortedByDateAsc);
+  }
+
+  @Test
+  public void givenEmpList_SortEmpList_thenCheckSortedList() {
+
+    Collections.sort(employees, new Comparator<Employee>() {
+      public int compare(Employee o1, Employee o2) {
+        return o1.getJoiningDate().compareTo(o2.getJoiningDate());
+      }
+    });
+
+    assertEquals(employees, employeesSortedByDateAsc);
+  }
+
+  @Test
+  public void givenEmpList_SortEmpList_thenCheckSortedListV1() {
+
+    Collections.sort(employees, new Comparator<Employee>() {
+      public int compare(Employee emp1, Employee emp2) {
+        if (emp1.getJoiningDate() == null || emp2.getJoiningDate() == null)
+          return 0;
+        return emp1.getJoiningDate().compareTo(emp2.getJoiningDate());
+      }
+    });
+
+    assertEquals(employees, employeesSortedByDateAsc);
+  }
+
+  @Test
+  public void givenEmpList_SortEmpList_thenSortedListinAscOrder() {
+    Collections.sort(employees, Collections.reverseOrder());
+
+    assertEquals(employees, employeesSortedByDateDesc);
+  }
+
+  @Test
+  public void givenEmpList_SortEmpList_thenCheckSortedListAsc() {
+
+    Collections.sort(employees, new Comparator<Employee>() {
+      public int compare(Employee emp1, Employee emp2) {
+        return emp2.getJoiningDate().compareTo(emp1.getJoiningDate());
+      }
+    });
+
+    assertEquals(employees, employeesSortedByDateDesc);
+  }
+
+  @Test
+  public void givenEmpList_SortEmpList_thenCheckSortedListAscV1() {
+
+    Collections.sort(employees, new Comparator<Employee>() {
+      public int compare(Employee emp1, Employee emp2) {
+        if (emp1.getJoiningDate() == null || emp2.getJoiningDate() == null)
+          return 0;
+        return emp2.getJoiningDate().compareTo(emp1.getJoiningDate());
+      }
+    });
+
+    assertEquals(employees, employeesSortedByDateDesc);
+  }
+
+  @Test
+  public void givenEmpList_SortEmpList_thenCheckSortedListDescLambda() {
+
+    Collections.sort(employees,
+      (emp1, emp2) -> emp2.getJoiningDate().compareTo(emp1.getJoiningDate()));
+
+    assertEquals(employees, employeesSortedByDateDesc);
+  }
+
+  @Test
+  public void givenEmpList_SortEmpList_thenCheckSortedListDescLambdaV1() {
+
+    Collections.sort(employees, (emp1, emp2) -> {
+      if (emp1.getJoiningDate() == null || emp2.getJoiningDate() == null)
+        return 0;
+      return emp2.getJoiningDate().compareTo(emp1.getJoiningDate());
+    });
+
+    assertEquals(employees, employeesSortedByDateDesc);
+  }
+
+  @Test
+  public void givenEmpList_SortEmpList_thenCheckSortedListAscLambda() {
+    Collections.sort(employees,
+      Comparator.comparing(Employee::getJoiningDate));
+    assertEquals(employees, employeesSortedByDateAsc);
+  }
+
+}

persistence-modules/hibernate-queries/src/test/java/com/baeldung/hibernate/criteria/EmployeeCriteriaIntegrationTest.java

@@ -32,5 +32,4 @@ public class EmployeeCriteriaIntegrationTest {
         session.close();
         assertArrayEquals(expectedSortCritEmployeeList.toArray(), employeeCriteriaQueries.getAllEmployees().toArray());
     }
-
 }