Program untuk mesin kasir pengulangan ( java )

import java.util.Scanner;
import java.io.*;
public class stock
{
double st=0,ttl=0;
char tekan;
void input()throws IOException
 {
do
{
double ttl=0;

Scanner input=new Scanner (System.in);
System.out.print("Nama Barang :");
String nb=input.nextLine();

Scanner input1=new Scanner (System.in);
System.out.print("Stock Barang :");
int sb=input1.nextInt();

Scanner input2=new Scanner(System.in);
int i=1;
float n;
System.out.print("Masukan Banyaknya transaksi :");
n=input2.nextFloat();

while (i<=n){

System.out.println("Pembeli Ke-"+i);
Scanner input3=new Scanner(System.in);
System.out.print("Nama Pembeli :");
String np=input3.nextLine();

Scanner input4=new Scanner(System.in);
System.out.print("Jumlah Beli :");
int jb=input4.nextInt();

ttl+=jb;
i++;}

st=(sb-ttl);
System.out.println(" stock Barang :"+st);

Scanner input5=new Scanner(System.in);
System.out.print("Ulangi Lagi [y]/[t] :");
String tanya=input5.nextLine();
tekan=tanya.charAt(0);

if ((tekan=='y')||(tekan=='Y')){
}
else if ((tekan=='t')||(tekan=='T')){
System.exit(0);}
else
{
Scanner input6=new Scanner(System.in);
System.out.print("Pilih Hanya [Y] atau [T] :");
String tanya1=input6.nextLine();
tekan=tanya1.charAt(0);
if ((tekan=='t')||(tekan=='T')){
System.exit(0);
}
  }
}
while (tekan !='t');
 }
public static void main (String[]args) throws IOException{
stock wrk= new stock();
wrk.input();
System.exit(0);
}
}