Sort an list object in the same order of another array java

Question

Hello I have I want to order a list of employee for department objects but I have the order in an array here the objects and the example

public class Employee {

    private String name;
    private int age;
    private double salary;
    private Department department;
    public Employee(String name, int age, double salary, Department department) {
        ...
    }

    // standard getters, setters and toString
 }

public class Department  {

    private Integer id;
    private String name;

    public Department(Integer id, String name) {
        ...
    }

    // standard getters, setters and toString
}


       Department[] departments = new Department[] {
                new Department(1, "Computing" ), new Department(2, "Human Resources"),
                new Department(3, "administration"), new Department(4, "operations"),
                new Department(5, "marketing"), new Department(6, "communication")
        };

  Employee[] employees = new Employee[] {
                new Employee("John", 23, 5000, departments[5]), new Employee("Steve", 26, 6000, departments[3]),
                new Employee("Frank", 33, 7000,departments[4]), new Employee("Earl", 43, 10000, departments[2]),
                new Employee("Jessica", 23, 4000, departments[1]), new Employee("Pearl", 33, 6000, departments[0])};


        String[] arrOrderDepartment = new String[]{"marketing", "Computing", "administration", "Human Resources", "communication", "operations"};

the bottom line is the employees ordered by the order of the department arrangement


employeesSortedByDepartment = [Employee{"Frank", 33, 7000, Department{id=5, name='marketing'}},Employee{ "Jessica", 23, 4000, Department{id=6, name='communication'} },Employee{"Steve", 26, 6000, Department{id=3, name='administration'} },Employee{"Earl", 43, 10000, Department{id=2, name='Human Resources'}},Employee{ "Pearl", 33, 6000, =Department{id=6, name='communication'} },Employee{ "John", 23, 5000, Department{id=4, name='operations'} }];

I have used something while working but it does not give me the expected result


 Collections.sort(department, new Comparator<String>(){
            public int compare(String left, String right) {
                return arrOrderDepartment[stringList.indexOf(left)] - arrOrder[stringList.indexOf(right)];
            }
        });

i am using java 6

thank you very much in what you can help me

Arvind Kumar Avinash · Answer 1 · 2020-04-22T08:02:22.423

You can do it as follows:

public class Main {
    public static void main(String[] args) {
        Department[] departments = new Department[] { new Department(1, "Computing"),
                new Department(2, "Human Resources"), new Department(3, "administration"),
                new Department(4, "operations"), new Department(5, "marketing"), new Department(6, "communication") };

        Employee[] employees = new Employee[] { new Employee("John", 23, 5000, departments[5]),
                new Employee("Steve", 26, 6000, departments[3]), new Employee("Frank", 33, 7000, departments[4]),
                new Employee("Earl", 43, 10000, departments[2]), new Employee("Jessica", 23, 4000, departments[1]),
                new Employee("Pearl", 33, 6000, departments[0]) };

        String[] arrOrderDepartment = new String[] { "marketing", "Computing", "administration", "Human Resources",
                "communication", "operations" };
        Employee[] employeesSortedByDepartment = new Employee[employees.length];
        for (int i = 0; i < arrOrderDepartment.length; i++) {
            employeesSortedByDepartment[i] = getEmployeeByDeptId(employees,
                    findDeptIdByDeptName(departments, arrOrderDepartment[i]));
        }
        for (Employee employee : employeesSortedByDepartment) {
            System.out.println(employee);
        }
    }

    static int findDeptIdByDeptName(Department[] departments, String departmentName) {
        for (int i = 0; i < departments.length; i++) {
            if (departments[i].getName().equalsIgnoreCase(departmentName)) {
                return departments[i].getId();
            }
        }
        return -1;
    }

    static Employee getEmployeeByDeptId(Employee[] employees, int id) {
        for (Employee employee : employees) {
            if (employee.getDepartment().getId() == id) {
                return employee;
            }
        }
        return null;
    }
}

Output:

Employee [name=Frank, age=33, salary=7000.0, department=Department [id=5, name=marketing]]
Employee [name=Pearl, age=33, salary=6000.0, department=Department [id=1, name=Computing]]
Employee [name=Earl, age=43, salary=10000.0, department=Department [id=3, name=administration]]
Employee [name=Jessica, age=23, salary=4000.0, department=Department [id=2, name=Human Resources]]
Employee [name=John, age=23, salary=5000.0, department=Department [id=6, name=communication]]
Employee [name=Steve, age=26, salary=6000.0, department=Department [id=4, name=operations]]

@ammf18 - I can see that you have edited your question. I've updated the answer based on your updated question. Let me know in case of any doubt/issue. — Arvind Kumar Avinash, Apr 22 '20 at 08:03

score 0 · Answer 2 · answered Apr 21 '20 at 16:17

Since your array of departments is already in order 1-6, you don't need to "sort" - what you need to do is apply the order that you want.

int[] arrOrderDepartment = {5, 1, 3, 2, 6, 4};

Department[] sortedDepartment = new Department[6];
for (int i = 0; i < 6; i++) {
    sortedDepartment[i] = department[arrOrderDepartment[i] - 1]
}

Now sortedDepartment[0] will point to the department 5, and sortedDepartment[1] will point to the department 1, and so on.

I made a new proposal to the topic – ammf18 Apr 21 '20 at 21:53 — ammf18, Apr 21 '20 at 21:53

score 0 · Answer 3 · answered Apr 21 '20 at 17:02

0

I think you can solve this with comparable fom Java 8 (I believe).

Here is the oracle document at this link. https://docs.oracle.com/javase/8/docs/api/java/lang/Comparable.html

And this link has an example of your question. How to sort an array of objects in Java?

answered Apr 21 '20 at 17:02

Andrey Rosa

71
5

OP has clearly mentioned that he/she is using Java 6. – Arvind Kumar Avinash Apr 21 '20 at 17:09
Ahhh sory my mistake – Andrey Rosa Apr 21 '20 at 17:14
if java 6, but I made a new proposal to the topic – ammf18 Apr 21 '20 at 21:53

score 0 · Accepted Answer · answered Apr 22 '20 at 13:59

thank you for your answer, yesterday from both analyzing and testing I got the solution contains something similar to the answer Arvind Kumar Avinash! gave me here I put the code

public class Main {

    public static void main(String[] args) {

        Department[] departments = new Department[] {
                new Department(1, "Computing" ), new Department(2, "Human Resources"),
                new Department(3, "administration"), new Department(4, "operations"),
                new Department(5, "marketing"), new Department(6, "communication"),
                new Department(7, "shopping"), new Department(6, "Inventory")
        };

        final Employee[] employees = new Employee[] {
                new Employee("John", 23, 5000, departments[5]), new Employee("Steve", 26, 6000, departments[3]),
                new Employee("Frank", 33, 7000,departments[4]), new Employee("Earl", 43, 10000, departments[2]),
                new Employee("Jessica", 23, 4000, departments[1]), new Employee("Pearl", 33, 6000, departments[0]),
                new Employee("Pearl", 33, 6000, departments[6]), new Employee("Pearl", 33, 6000, departments[7])
        };


       final String[] arrOrderDepartment = new String[]{"operations", "Computing", "administration", "Inventory", "Human Resources", "communication", "marketing"};

        final List<Employee> employeeList = Arrays.asList(employees);
        List<Employee> copyEmployeeList = Arrays.asList(employees);

        Collections.sort(copyEmployeeList, new Comparator<Employee>(){

            public int compare(Employee o1, Employee o2)
            {
                String a = getDepartmentOfList(o1.getDepartment().getName(), employeeList);
                String b = getDepartmentOfList(o2.getDepartment().getName(), employeeList);

              return  indexOf(a, arrOrderDepartment) - indexOf(b, arrOrderDepartment);
            }
        });

        System.out.println(copyEmployeeList);
    }

    private static String getDepartmentOfList(String name, List<Employee> employeeList) {
        for (Employee employee: employeeList) {
            if (name.equalsIgnoreCase(employee.getDepartment().getName())){
                return employee.getDepartment().getName();
            }
        }
        return null;
    }

    private static int indexOf( String c , String[] arr ) {
        for( int i = 0 ; i < arr.length ; i++ ) {
            if( arr[i].equalsIgnoreCase(c) ) {
                return i;
            }
        }
        return -1;
    }
}

add other departments to see how the code behaved and add it firstadd other departments to see how the code behaved and add it first

Sort an list object in the same order of another array java

4 Answers4