public class Pesan {
    String nama, tipe, gula;
    Integer harga, qty;

    public Pesan(String nama, String tipe, String gula, Integer harga, Integer qty) {
        this.nama = nama;
        this.tipe = tipe;
        this.gula = gula;
        this.harga = harga;
        this.qty = qty;
    }

    public String getNama() {
        return nama;
    }

    public String getTipe() {
        return tipe;
    }

    public String getGula() {
        return gula;
    }

    public Integer getHarga() {
        return harga;
    }

    public Integer getQty() {
        return qty;
    }
}



=================== bikin file baru

import java.util.ArrayList;
import java.util.Scanner;

public class JavaApplication1 {

    public static void main(String[] args) {
        ArrayList<Pesan> p = new ArrayList();
        Scanner sc = new Scanner(System.in);
        Integer pilihan = 0;

       do{
           /*
           jika pilih 1, maka input data,
           jika 2, maka tampilkan data
           jika 3 maka keluar sistem
           */

            System.out.println("----------------------------");
            System.out.println("--- BINTANG BUCK COFFEE ----");
            System.out.println("----------------------------");
            System.out.println("  1. Pembelian");
            System.out.println("  2. Bayar");
            System.out.println("  3. Keluar sistem");
            System.out.println("----------------------------");
            System.out.print("  Pilihanmu: ");
            pilihan = sc.nextInt();

           if(pilihan == 1 ){
               p = beli( p );
           }else if(pilihan == 2){
                p = bayar( p );
           }
       }while (pilihan != 3);

    }

    private static ArrayList<Pesan> beli( ArrayList<Pesan> p ){
        Scanner sc = new Scanner(System.in);
        String nama, tipe, gula;
        Integer harga, qty;

        System.out.print("Nama: ");
        nama = sc.nextLine();

        System.out.print("Tipe: ");
        tipe = sc.nextLine();

        System.out.print("Gula: ");
        gula = sc.nextLine();

        System.out.print("Harga: ");
        harga = sc.nextInt();

        System.out.print("Qty: ");
        qty = sc.nextInt();

        p.add( new Pesan( nama, tipe, gula, harga, qty ) );

        return p;
    }

    private static ArrayList<Pesan> bayar( ArrayList<Pesan> p ){
        Scanner sc = new Scanner(System.in);

        //tampilkan data
        System.out.println("Jumlah data: "+ p.size()); //ini error
        System.out.println("--------------------------------------------------------------------");
        System.out.printf("| %-3s | %-10s | %-10s | %-5s | %-7s | %-3s  | %-7s |",
                "No",
                "Nama",
                "Tipe",
                "Gula",
                "Harga",
                "Qty",
                "Jumlah");
        System.out.println();
        System.out.println("--------------------------------------------------------------------");

        for(int i = 0; i < p.size(); i++ ){
            System.out.printf("| %-3s | %-10s | %-10s | %-5s | %-7s | %-3s  | %-7s |",
                i + 1,
                p.get(i).getNama(),
                p.get(i).getTipe(),
                p.get(i).getGula(),
                p.get(i).getHarga(),
                p.get(i).getQty(),
                (p.get(i).getHarga() * p.get(i).getQty()));
            System.out.println();
            System.out.println("--------------------------------------------------------------------");

        }

        System.out.println("Tekan enter untuk lanjut...");
        sc.nextLine();

        return p;
    }
}