Making a list of cities using Vectors in Java

program to add city name in the list ,delete city and display city
       *if city exist  print  some message
       *if name already deleted print some message
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import java.util.*;
class City
{
Vector v=new Vector();

void addcity() // adding city name
{
Scanner sc=new Scanner(System.in);
System.out.println("enter name of city to be added");
String t=sc.nextLine();
int flag=0;
for(int i=0;i<v.size();i++)
{
if(v.elementAt(i).equals(t))//compares input name with each names in th list

{
System.out.println("City already added");//if name already added
flag=1;
}
}
if(flag==0) //if name  not added
{
v.addElement(t);
}


}
void deletecity() //delete city name
{ int flag=0;
Scanner sc=new Scanner(System.in);
System.out.println("enter name of city to be delete");
String str=sc.nextLine();
for(int i=0;i<v.size();i++)
{
if(v.elementAt(i).equals(str)) //if name exist
v.removeElementAt(i);
else
flag=1;
}
if(flag==0)
System.out.println("city dosen't exist in list");
}
void display()
{
for(int i=0;i<v.size();i++)
{
System.out.println(v.elementAt(i)); // if name not in list
}
}
}
class Demo
{
public static void main(String args[])
{City ci=new City();
Scanner sc=new Scanner(System.in);
do{System.out.println("1:add city\n2:remove city\n3:display all\n");
int n=sc.nextInt();
switch(n)
{
case 1:
ci.addcity();
break;
case 2:
ci.deletecity();
break;
case 3:
ci.display();
break;
default:
}
}while(true);
}
}
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output: