Program Can’t sort Employee List [closed]

I’am making a java program using streams which sort employee based on their salary. Program is given below :-

public class EmployeeMain {

    public static void main(String[] args) {

        Employee e1 = new Employee(10000, "Adam");
        Employee e2 = new Employee(5000, "Peter");
        Employee e3 = new Employee(14000, "Robin");

        List<Employee> list = Arrays.asList(e1, e2, e3);

        Collections.sort(list,
                (emp1, emp2) -> e1.getSalary() > e2.getSalary() ? 1 : e2.getSalary() > e1.getSalary() ? -1 : 0);

        list.stream().forEach(System.out::println);
        
    }

}

The output for this code is :-

Employee [salary=10000, name=Adam]
Employee [salary=5000, name=Peter]
Employee [salary=14000, name=Robin]

What’s the issue with this code?

Answer

You’ve made a typo in the body of the sort method. Instead of using emp1 and emp2 you used e1 and e2 which are the instances of the employees you instantiated above.

So basically what you wrote gets evaluated to :

Collections.sort(list, (emp1, emp2) -> 10000 > 5000 ? 1 : 5000 > 10000 ? -1 : 0)

Which is

Collections.sort(list, (emp1, emp2) -> 1)

What you want to write is

Collections.sort(list, (emp1, emp2) -> emp1.getSalary() > emp2.getSalary() ? 1 : emp2.getSalary() > emp1.getSalary() ? -1 : 0);

or shorter/better, as stated in the comments

list.sort(Comparator.comparingInt(Employee::getSalary));