Initial commit for Comparator.comparing article. (#1271)
* Initial commit for Comparator.comparing article. * Changes in the code as per suggestions in review.
This commit is contained in:
Parth Joshi
KevinGilmore
parent
19ff2eb487
commit
b7e74ce721
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package com.baeldung.java8.comparator;
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import lombok.AllArgsConstructor;
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import lombok.Data;
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import lombok.EqualsAndHashCode;
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import lombok.ToString;
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@Data
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@AllArgsConstructor
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@ToString
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@EqualsAndHashCode
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public class Employee implements Comparable<Employee>{
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String name;
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int age;
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double salary;
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long mobile;
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@Override
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public int compareTo(Employee argEmployee) {
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return name.compareTo(argEmployee.getName());
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}
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}
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package com.baeldung.java8.comparator;
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import java.util.Arrays;
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import java.util.Comparator;
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import org.junit.Before;
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import org.junit.Test;
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import lombok.Data;
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import static org.junit.Assert.assertTrue;
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public class Java8ComparatorTest {
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private Employee[] employees;
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private Employee[] employeesArrayWithNulls;
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private Employee[] sortedEmployeesByName;
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private Employee[] sortedEmployeesByNameDesc;
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private Employee[] sortedEmployeesByAge;
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private Employee[] sortedEmployeesByMobile;
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private Employee[] sortedEmployeesBySalary;
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private Employee[] sortedEmployeesArray_WithNullsFirst;
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private Employee[] sortedEmployeesArray_WithNullsLast;
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private Employee[] sortedEmployeesByNameAge;
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private Employee[] someMoreEmployees;
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private Employee[] sortedEmployeesByAgeName;;
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@Before
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public void initData() {
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employees = new Employee[] { new Employee("John", 25, 3000, 9922001), new Employee("Ace", 22, 2000, 5924001),
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new Employee("Keith", 35, 4000, 3924401) };
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employeesArrayWithNulls = new Employee[] { new Employee("John", 25, 3000, 9922001), null, new Employee("Ace", 22, 2000, 5924001),
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null, new Employee("Keith", 35, 4000, 3924401) };
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sortedEmployeesByName = new Employee[] { new Employee("Ace", 22, 2000, 5924001),
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new Employee("John", 25, 3000, 9922001), new Employee("Keith", 35, 4000, 3924401) };
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sortedEmployeesByNameDesc = new Employee[] { new Employee("Keith", 35, 4000, 3924401), new Employee("John", 25, 3000, 9922001),
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new Employee("Ace", 22, 2000, 5924001) };
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sortedEmployeesByAge = new Employee[] { new Employee("Ace", 22, 2000, 5924001),
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new Employee("John", 25, 3000, 9922001), new Employee("Keith", 35, 4000, 3924401) };
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sortedEmployeesByMobile = new Employee[] { new Employee("Keith", 35, 4000, 3924401), new Employee("Ace", 22, 2000, 5924001),
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new Employee("John", 25, 3000, 9922001), };
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sortedEmployeesBySalary = new Employee[] { new Employee("Ace", 22, 2000, 5924001), new Employee("John", 25, 3000, 9922001),
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new Employee("Keith", 35, 4000, 3924401), };
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sortedEmployeesArray_WithNullsFirst = new Employee[] { null, null, new Employee("Ace", 22, 2000, 5924001),
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new Employee("John", 25, 3000, 9922001), new Employee("Keith", 35, 4000, 3924401) };
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sortedEmployeesArray_WithNullsLast = new Employee[] { new Employee("Ace", 22, 2000, 5924001),
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new Employee("John", 25, 3000, 9922001), new Employee("Keith", 35, 4000, 3924401), null, null };
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someMoreEmployees = new Employee[] { new Employee("Jake", 25, 3000, 9922001), new Employee("Jake", 22, 2000, 5924001),
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new Employee("Ace", 22, 3000, 6423001), new Employee("Keith", 35, 4000, 3924401) };
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sortedEmployeesByAgeName = new Employee[] { new Employee("Ace", 22, 3000, 6423001),
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new Employee("Jake", 22, 2000, 5924001), new Employee("Jake", 25, 3000, 9922001), new Employee("Keith", 35, 4000, 3924401) };
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sortedEmployeesByNameAge = new Employee[] { new Employee("Ace", 22, 3000, 6423001),
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new Employee("Jake", 22, 2000, 5924001), new Employee("Jake", 25, 3000, 9922001), new Employee("Keith", 35, 4000, 3924401) };
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}
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@Test
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public void givenEmployeeArray_whenUsingComparing_thenCheckingSort() {
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Comparator<Employee> employeeNameComparator = Comparator.comparing(Employee::getName);
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Arrays.sort(employees, employeeNameComparator);
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// System.out.println(Arrays.toString(employees));
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assertTrue(Arrays.equals(employees, sortedEmployeesByName));
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}
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@Test
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public void givenEmployeeArray_whenUsingComparingWithComparator_thenCheckingSort() {
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Comparator<Employee> employeeNameComparator = Comparator.comparing(Employee::getName, (s1, s2) -> {
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return s2.compareTo(s1);
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});
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Arrays.sort(employees, employeeNameComparator);
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// System.out.println(Arrays.toString(employees));
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assertTrue(Arrays.equals(employees, sortedEmployeesByNameDesc));
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}
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@Test
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public void givenEmployeeArray_whenUsingComparingInt_thenCheckingSort() {
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Comparator<Employee> employeeAgeComparator = Comparator.comparingInt(Employee::getAge);
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Arrays.sort(employees, employeeAgeComparator);
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// System.out.println(Arrays.toString(employees));
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assertTrue(Arrays.equals(employees, sortedEmployeesByAge));
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}
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@Test
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public void givenEmployeeArray_whenUsingComparingLong_thenCheckingSort() {
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Comparator<Employee> employeeMobileComparator = Comparator.comparingLong(Employee::getMobile);
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Arrays.sort(employees, employeeMobileComparator);
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// System.out.println(Arrays.toString(employees));
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assertTrue(Arrays.equals(employees, sortedEmployeesByMobile));
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}
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@Test
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public void givenEmployeeArray_whenUsingComparingDouble_thenCheckingSort() {
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Comparator<Employee> employeeSalaryComparator = Comparator.comparingDouble(Employee::getSalary);
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Arrays.sort(employees, employeeSalaryComparator);
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// System.out.println(Arrays.toString(employees));
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assertTrue(Arrays.equals(employees, sortedEmployeesBySalary));
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}
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@Test
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public void givenEmployeeArray_whenUsingNaturalOrder_thenCheckingSort() {
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Comparator<Employee> employeeNameComparator = Comparator.<Employee> naturalOrder();
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Arrays.sort(employees, employeeNameComparator);
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// System.out.println(Arrays.toString(employees));
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assertTrue(Arrays.equals(employees, sortedEmployeesByName));
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}
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@Test
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public void givenEmployeeArray_whenUsingReverseOrder_thenCheckingSort() {
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Comparator<Employee> employeeNameComparator = Comparator.<Employee> reverseOrder();
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Arrays.sort(employees, employeeNameComparator);
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// System.out.println(Arrays.toString(employees));
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assertTrue(Arrays.equals(employees, sortedEmployeesByNameDesc));
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}
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@Test
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public void givenEmployeeArray_whenUsingNullFirst_thenCheckingSort() {
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Comparator<Employee> employeeNameComparator = Comparator.comparing(Employee::getName);
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Comparator<Employee> employeeNameComparator_nullFirst = Comparator.nullsFirst(employeeNameComparator);
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Arrays.sort(employeesArrayWithNulls, employeeNameComparator_nullFirst);
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// System.out.println(Arrays.toString(employeesArrayWithNulls));
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assertTrue(Arrays.equals(employeesArrayWithNulls, sortedEmployeesArray_WithNullsFirst));
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}
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@Test
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public void givenEmployeeArray_whenUsingNullLast_thenCheckingSort() {
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Comparator<Employee> employeeNameComparator = Comparator.comparing(Employee::getName);
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Comparator<Employee> employeeNameComparator_nullLast = Comparator.nullsLast(employeeNameComparator);
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Arrays.sort(employeesArrayWithNulls, employeeNameComparator_nullLast);
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// System.out.println(Arrays.toString(employeesArrayWithNulls));
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assertTrue(Arrays.equals(employeesArrayWithNulls, sortedEmployeesArray_WithNullsLast));
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}
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@Test
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public void givenEmployeeArray_whenUsingThenComparing_thenCheckingSort() {
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Comparator<Employee> employee_Age_Name_Comparator = Comparator.comparing(Employee::getAge).thenComparing(Employee::getName);
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Arrays.sort(someMoreEmployees, employee_Age_Name_Comparator);
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// System.out.println(Arrays.toString(someMoreEmployees));
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assertTrue(Arrays.equals(someMoreEmployees, sortedEmployeesByAgeName));
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}
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@Test
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public void givenEmployeeArray_whenUsingThenComparingInt_thenCheckingSort() {
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Comparator<Employee> employee_Name_Age_Comparator = Comparator.comparing(Employee::getName).thenComparingInt(Employee::getAge);
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Arrays.sort(someMoreEmployees, employee_Name_Age_Comparator);
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// System.out.println(Arrays.toString(someMoreEmployees));
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assertTrue(Arrays.equals(someMoreEmployees, sortedEmployeesByNameAge));
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}
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@Before
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public void printData() {
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// System.out.println("employees");
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// System.out.println(Arrays.toString(employees));
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//
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// System.out.println("employeesArrayWithNulls");
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// System.out.println(Arrays.toString(employeesArrayWithNulls));
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//
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// System.out.println("sortedEmployeesByName");
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// System.out.println(Arrays.toString(sortedEmployeesByName));
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//
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// System.out.println("sortedEmployeesByNameDesc");
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// System.out.println(Arrays.toString(sortedEmployeesByNameDesc));
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//
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// System.out.println("sortedEmployeesByAge");
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// System.out.println(Arrays.toString(sortedEmployeesByAge));
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//
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// System.out.println("sortedEmployeesByMobile");
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// System.out.println(Arrays.toString(sortedEmployeesByMobile));
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//
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// System.out.println("sortedEmployeesBySalary");
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// System.out.println(Arrays.toString(sortedEmployeesBySalary));
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//
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// System.out.println("sortedEmployeesArray_WithNullsFirst");
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// System.out.println(Arrays.toString(sortedEmployeesArray_WithNullsFirst));
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//
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// System.out.println("sortedEmployeesArray_WithNullsLast");
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// System.out.println(Arrays.toString(sortedEmployeesArray_WithNullsLast));
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//
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// System.out.println("sortedEmployeesByNameAge");
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// System.out.println(Arrays.toString(sortedEmployeesByNameAge));
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//
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// System.out.println("someMoreEmployees");
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// System.out.println(Arrays.toString(someMoreEmployees));
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//
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}
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}
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