com.google.firebase.database.DatabaseException: Failed to convert a value of type java.lang.String to long

public class Cart {

    private String pid, pname, price;
    private Long discount, quantity;

    public Cart() {
    }

    public Cart(String pid, String pname, String price, Long discount, Long quantity) {
        this.pid = pid;
        this.pname = pname;
        this.price = price;
        this.discount = discount;
        this.quantity = quantity;
    }

    public String getPid() {
        return pid;
    }

    public void setPid(String pid) {
        this.pid = pid;
    }

    public String getPname() {
        return pname;
    }

    public void setPname(String pname) {
        this.pname = pname;
    }

    public String getPrice() {
        return price;
    }

    public void setPrice(String price) {
        this.price = price;
    }

    public Long getDiscount() {
        return discount;
    }

    public void setDiscount(Long discount) {
        this.discount = discount;
    }

    public Long getQuantity() {
        return quantity;
    }

    public void setQuantity(Long quantity) {
        this.quantity = quantity;
    }
}