Question 7: Given the list of employee, group them by employee name?

 Answer:

You can use Collections.groupBy() to group list of employees by employee name.

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
 
public class MaximumUsingStreamMain {
    public static void main(String args[])
    {
        List<Employee> employeeList = createEmployeeList();
        Map<String, List<Employee>> map = employeeList.stream()
                                              .collect(Collectors.groupingBy(Employee::getName));
        map.forEach((name,employeeListTemp)->System.out.println("Name: "+name+" ==>"+employeeListTemp));
    }
 
    public static List<Employee> createEmployeeList()
    {
        List<Employee> employeeList=new ArrayList<>();
 
        Employee e1=new Employee("John",21);
        Employee e2=new Employee("Martin",19);
        Employee e3=new Employee("Mary",31);
        Employee e4=new Employee("Mary",18);
        Employee e5=new Employee("John",26);
 
        employeeList.add(e1);
        employeeList.add(e2);
        employeeList.add(e3);
        employeeList.add(e4);
        employeeList.add(e5);
 
        return employeeList;
    }
}

Output:

Name: John ==>[Employee Name: John age: 21, Employee Name: John age: 26]
Name: Martin ==>[Employee Name: Martin age: 19] 
Name: Mary ==>[Employee Name: Mary age: 31, Employee Name: Mary age: 18]

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