iSharkFly-Docs
/
java-tutorials
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

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 2017-03-13 08:33:21 +05:30 committed by KevinGilmore
parent 19ff2eb487
commit b7e74ce721
2 changed files with 215 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
core-java/src/test/java/com/baeldung/java8/comparator/Employee.java Normal file
View File

@ -0,0 +1,23 @@
package com.baeldung.java8.comparator;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.EqualsAndHashCode;
import lombok.ToString;
@Data
@AllArgsConstructor
@ToString
@EqualsAndHashCode
public class Employee implements Comparable<Employee>{
String name;
int age;
double salary;
long mobile;
@Override
public int compareTo(Employee argEmployee) {
return name.compareTo(argEmployee.getName());
}
}

192
core-java/src/test/java/com/baeldung/java8/comparator/Java8ComparatorTest.java Normal file
View File

@ -0,0 +1,192 @@
package com.baeldung.java8.comparator;
import java.util.Arrays;
import java.util.Comparator;
import org.junit.Before;
import org.junit.Test;
import lombok.Data;
import static org.junit.Assert.assertTrue;
public class Java8ComparatorTest {
private Employee[] employees;
private Employee[] employeesArrayWithNulls;
private Employee[] sortedEmployeesByName;
private Employee[] sortedEmployeesByNameDesc;
private Employee[] sortedEmployeesByAge;
private Employee[] sortedEmployeesByMobile;
private Employee[] sortedEmployeesBySalary;
private Employee[] sortedEmployeesArray_WithNullsFirst;
private Employee[] sortedEmployeesArray_WithNullsLast;
private Employee[] sortedEmployeesByNameAge;
private Employee[] someMoreEmployees;
private Employee[] sortedEmployeesByAgeName;;
@Before
public void initData() {
employees = new Employee[] { new Employee("John", 25, 3000, 9922001), new Employee("Ace", 22, 2000, 5924001),
new Employee("Keith", 35, 4000, 3924401) };
employeesArrayWithNulls = new Employee[] { new Employee("John", 25, 3000, 9922001), null, new Employee("Ace", 22, 2000, 5924001),
null, new Employee("Keith", 35, 4000, 3924401) };
sortedEmployeesByName = new Employee[] { new Employee("Ace", 22, 2000, 5924001),
new Employee("John", 25, 3000, 9922001), new Employee("Keith", 35, 4000, 3924401) };
sortedEmployeesByNameDesc = new Employee[] { new Employee("Keith", 35, 4000, 3924401), new Employee("John", 25, 3000, 9922001),
new Employee("Ace", 22, 2000, 5924001) };
sortedEmployeesByAge = new Employee[] { new Employee("Ace", 22, 2000, 5924001),
new Employee("John", 25, 3000, 9922001), new Employee("Keith", 35, 4000, 3924401) };
sortedEmployeesByMobile = new Employee[] { new Employee("Keith", 35, 4000, 3924401), new Employee("Ace", 22, 2000, 5924001),
new Employee("John", 25, 3000, 9922001), };
sortedEmployeesBySalary = new Employee[] { new Employee("Ace", 22, 2000, 5924001), new Employee("John", 25, 3000, 9922001),
new Employee("Keith", 35, 4000, 3924401), };
sortedEmployeesArray_WithNullsFirst = new Employee[] { null, null, new Employee("Ace", 22, 2000, 5924001),
new Employee("John", 25, 3000, 9922001), new Employee("Keith", 35, 4000, 3924401) };
sortedEmployeesArray_WithNullsLast = new Employee[] { new Employee("Ace", 22, 2000, 5924001),
new Employee("John", 25, 3000, 9922001), new Employee("Keith", 35, 4000, 3924401), null, null };
someMoreEmployees = new Employee[] { new Employee("Jake", 25, 3000, 9922001), new Employee("Jake", 22, 2000, 5924001),
new Employee("Ace", 22, 3000, 6423001), new Employee("Keith", 35, 4000, 3924401) };
sortedEmployeesByAgeName = new Employee[] { new Employee("Ace", 22, 3000, 6423001),
new Employee("Jake", 22, 2000, 5924001), new Employee("Jake", 25, 3000, 9922001), new Employee("Keith", 35, 4000, 3924401) };
sortedEmployeesByNameAge = new Employee[] { new Employee("Ace", 22, 3000, 6423001),
new Employee("Jake", 22, 2000, 5924001), new Employee("Jake", 25, 3000, 9922001), new Employee("Keith", 35, 4000, 3924401) };
}
@Test
public void givenEmployeeArray_whenUsingComparing_thenCheckingSort() {
Comparator<Employee> employeeNameComparator = Comparator.comparing(Employee::getName);
Arrays.sort(employees, employeeNameComparator);
// System.out.println(Arrays.toString(employees));
assertTrue(Arrays.equals(employees, sortedEmployeesByName));
}
@Test
public void givenEmployeeArray_whenUsingComparingWithComparator_thenCheckingSort() {
Comparator<Employee> employeeNameComparator = Comparator.comparing(Employee::getName, (s1, s2) -> {
return s2.compareTo(s1);
});
Arrays.sort(employees, employeeNameComparator);
// System.out.println(Arrays.toString(employees));
assertTrue(Arrays.equals(employees, sortedEmployeesByNameDesc));
}
@Test
public void givenEmployeeArray_whenUsingComparingInt_thenCheckingSort() {
Comparator<Employee> employeeAgeComparator = Comparator.comparingInt(Employee::getAge);
Arrays.sort(employees, employeeAgeComparator);
// System.out.println(Arrays.toString(employees));
assertTrue(Arrays.equals(employees, sortedEmployeesByAge));
}
@Test
public void givenEmployeeArray_whenUsingComparingLong_thenCheckingSort() {
Comparator<Employee> employeeMobileComparator = Comparator.comparingLong(Employee::getMobile);
Arrays.sort(employees, employeeMobileComparator);
// System.out.println(Arrays.toString(employees));
assertTrue(Arrays.equals(employees, sortedEmployeesByMobile));
}
@Test
public void givenEmployeeArray_whenUsingComparingDouble_thenCheckingSort() {
Comparator<Employee> employeeSalaryComparator = Comparator.comparingDouble(Employee::getSalary);
Arrays.sort(employees, employeeSalaryComparator);
// System.out.println(Arrays.toString(employees));
assertTrue(Arrays.equals(employees, sortedEmployeesBySalary));
}
@Test
public void givenEmployeeArray_whenUsingNaturalOrder_thenCheckingSort() {
Comparator<Employee> employeeNameComparator = Comparator.<Employee> naturalOrder();
Arrays.sort(employees, employeeNameComparator);
// System.out.println(Arrays.toString(employees));
assertTrue(Arrays.equals(employees, sortedEmployeesByName));
}
@Test
public void givenEmployeeArray_whenUsingReverseOrder_thenCheckingSort() {
Comparator<Employee> employeeNameComparator = Comparator.<Employee> reverseOrder();
Arrays.sort(employees, employeeNameComparator);
// System.out.println(Arrays.toString(employees));
assertTrue(Arrays.equals(employees, sortedEmployeesByNameDesc));
}
@Test
public void givenEmployeeArray_whenUsingNullFirst_thenCheckingSort() {
Comparator<Employee> employeeNameComparator = Comparator.comparing(Employee::getName);
Comparator<Employee> employeeNameComparator_nullFirst = Comparator.nullsFirst(employeeNameComparator);
Arrays.sort(employeesArrayWithNulls, employeeNameComparator_nullFirst);
// System.out.println(Arrays.toString(employeesArrayWithNulls));
assertTrue(Arrays.equals(employeesArrayWithNulls, sortedEmployeesArray_WithNullsFirst));
}
@Test
public void givenEmployeeArray_whenUsingNullLast_thenCheckingSort() {
Comparator<Employee> employeeNameComparator = Comparator.comparing(Employee::getName);
Comparator<Employee> employeeNameComparator_nullLast = Comparator.nullsLast(employeeNameComparator);
Arrays.sort(employeesArrayWithNulls, employeeNameComparator_nullLast);
// System.out.println(Arrays.toString(employeesArrayWithNulls));
assertTrue(Arrays.equals(employeesArrayWithNulls, sortedEmployeesArray_WithNullsLast));
}
@Test
public void givenEmployeeArray_whenUsingThenComparing_thenCheckingSort() {
Comparator<Employee> employee_Age_Name_Comparator = Comparator.comparing(Employee::getAge).thenComparing(Employee::getName);
Arrays.sort(someMoreEmployees, employee_Age_Name_Comparator);
// System.out.println(Arrays.toString(someMoreEmployees));
assertTrue(Arrays.equals(someMoreEmployees, sortedEmployeesByAgeName));
}
@Test
public void givenEmployeeArray_whenUsingThenComparingInt_thenCheckingSort() {
Comparator<Employee> employee_Name_Age_Comparator = Comparator.comparing(Employee::getName).thenComparingInt(Employee::getAge);
Arrays.sort(someMoreEmployees, employee_Name_Age_Comparator);
// System.out.println(Arrays.toString(someMoreEmployees));
assertTrue(Arrays.equals(someMoreEmployees, sortedEmployeesByNameAge));
}
@Before
public void printData() {
// System.out.println("employees");
// System.out.println(Arrays.toString(employees));
//
// System.out.println("employeesArrayWithNulls");
// System.out.println(Arrays.toString(employeesArrayWithNulls));
//
// System.out.println("sortedEmployeesByName");
// System.out.println(Arrays.toString(sortedEmployeesByName));
//
// System.out.println("sortedEmployeesByNameDesc");
// System.out.println(Arrays.toString(sortedEmployeesByNameDesc));
//
// System.out.println("sortedEmployeesByAge");
// System.out.println(Arrays.toString(sortedEmployeesByAge));
//
// System.out.println("sortedEmployeesByMobile");
// System.out.println(Arrays.toString(sortedEmployeesByMobile));
//
// System.out.println("sortedEmployeesBySalary");
// System.out.println(Arrays.toString(sortedEmployeesBySalary));
//
// System.out.println("sortedEmployeesArray_WithNullsFirst");
// System.out.println(Arrays.toString(sortedEmployeesArray_WithNullsFirst));
//
// System.out.println("sortedEmployeesArray_WithNullsLast");
// System.out.println(Arrays.toString(sortedEmployeesArray_WithNullsLast));
//
// System.out.println("sortedEmployeesByNameAge");
// System.out.println(Arrays.toString(sortedEmployeesByNameAge));
//
// System.out.println("someMoreEmployees");
// System.out.println(Arrays.toString(someMoreEmployees));
//
}
}