I have java custom class i.e Employee having below fields,
public class Employee {
private String name;
private String dept;
private Integer age;
private Double salary;
}
public Employee(String name, String dept, Integer age, Double salary) {
this.name = name;
this.dept = dept;
this.salary = salary;
this.age = age;
}
//getter and setters
My list object has below data,
List<Employee> list = Arrays.asList(
new Employee("mahesh", "IT", 25, 1000.00),
new Employee("rajesh", "IT", 30, 1200.00),
new Employee("Saket", "IT", 30, 1000.00),
new Employee("Samuel", "IT", 30, 1150.00),
new Employee("Anil", "Eng", 29, 2000.00),
new Employee("Sachin", "Eng", 29, 2000.00));
I have to iterate this list and updated list should return first, third, fifth and sixth records. group the records using department and salary and if the grouping count greater than 1 those records should return. In the above example, second and fourth it's occured one time as grouping so those records should skip.
So final List should contain these records,
List<Employee> list = Arrays.asList(
new Employee("mahesh", "IT", 25, 1000.00),
new Employee("Saket", "IT", 30, 1000.00),
new Employee("Anil", "Eng", 29, 2000.00),
new Employee("Sachin", "Eng", 29, 2000.00));
Need to group based on two fields i.e department and salary and the stream api should return updated list.
If you are interested in elements that are not unique when grouped by a combination of department and salary, you can perform a grouping and filter based on the count. This would further need flat mapping the elements back for the data structure desired in the output:
List<Employee> employees = list.stream()
.collect(Collectors.groupingBy(employee -> employee.dept + employee.salary))
.entrySet()
.stream()
.filter(e -> e.getValue().size() > 1)
.flatMap(e -> e.getValue().stream())
.collect(Collectors.toList());
Note: This relies on the uniqueness of the key created with the combination of department and salary represented as of type String.