Finden Sie, wie Sie Mitarbeiter details,aktualisieren,entfernen,anzeigen mit hashmap

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;

class Employee
{
private String Id;
private String Name;
private String Department;
private String Salary;

public Employee(String Id, String Name, String Department,
String Salary)
{
this.Id=Id;
this.Name=Name;
this.Department=Department;
this.Salary=Salary;
}

public String getId() {
return Id;
}
public void setId(String id) {
Id = id;
}
public String getName() {
return Name;
}
public void setName(String name) {
Name = name;
}
public String getDepartment() {
return Department;
}
public void setDepartment(String department) {
Department = department;
}
public String getSalary() {
return Salary;
}
public void setSalary(String salary) {
Salary = salary;
}

public String toString() 
{ 
return this.Id+"\t"+this.Name+"\t\t"+this.Department+"\t\t\t"+this.Salary;
}
}


public class Assignment4 
{
public static void main(String[] args)
{

try {

Map< String, List<Employee> > m=new HashMap< String, List<Employee> >();
List<Employee> ListForFinance=new ArrayList<Employee>();
Scanner scn1=new Scanner(System.in);
String Id;
String Name;
String Department;
String Salary;

while(true)
{
System.out.print("\nThe Choices:\n1>add\n2>modification\n3>remove\n4>display\n\n");
System.out.println("Enter the choice: ");
System.out.println("To quit type -1");
int num=scn1.nextInt();
if(num == -1)
{
break;
}

switch(num)
{
case 1:
{
System.out.print("\nDepartment: ");
Department=scn1.next();
System.out.print("\nId: ";
Id=scn1.next();
System.out.print("\nName: ");
Name=scn1.next();
System.out.print("\nSalary: ");
Salary=scn1.next();

Employee employee1=new Employee(Id,Name,Department,Salary);
ListForFinance.add(employee1);
m.put(Department, ListForFinance);
break;
}

case 2:
{
System.out.println("Type Department to be modified");
Department=scn1.next();
System.out.println("Modification values");
System.out.print("\nId: ");
Id=scn1.next();
System.out.print("\nName: ");
Name=scn1.next();
System.out.print("\nSalary: ";
Salary=scn1.next();

Set<String> s=m.keySet();
Iterator<String> i=s.iterator();

Employee employee1=new Employee(Id,Name,Department,Salary);
m.get(Department.setId("Id");
ListForFinance.add(employee1);
m.put(Department, ListForFinance);

while(i.hasNext())
{
System.out.println(i.next());
}

break;
}



case 3:
{
System.out.println("=========================================================");
System.out.println("ID"+"\t"+"NAME"+"\t\t"+"DEPARTMENT"+"\t\t"+"SALARY");
System.out.println("=========================================================");
Set<String> s=m.keySet();
Iterator<String> i=s.iterator();

while(i.hasNext()) 
{
     String dept=i.next();
     List<Employee> employees=m.get(dept);
     for(int j=0;j<employees.size();j++)
     {
         System.out.print("\n"+employees.get(j)+"\n\n"); 
     }  
}
break;
}

}
}
}

catch(Exception e)
{
System.out.println("NOTE: \n"+"Please enter specified key format..!!!");
System.out.println("======================================");
System.out.println("Now you are Signing out");
System.out.println("Thank You,Login Again");
System.out.println("======================================"); 
}
}
}

default:
System.out.println("=============================================================";
System.out.print("Wrong key Pressed,please enter the correct key\n";
System.out.println("Try again...!!!";
System.out.println("=============================================================";
}
}
} 


Please find how to enter employee details,update,remove,displaying using hashmap wherin employee dept is taken as a key and id,name,salary is stored in the values using arraylist ......Currently Iam struck at CASE 2...PLease help me out

In FALL 1 bin ich versucht, legen die Mitarbeiter details und in FALL 2 iam versucht, ändern Sie die Werte .Wenn ich versuche, um alle details mit dem gleichen Dept es sollte neuen Eintrag erstellen...Auch ich sollte in der Lage, es zu ändern,bin ich nicht immer, wie zu tun..Bitte helfen Sie mir