8. วัตถุสิ่งของ

public class BankAccount {
  private String id;    // หมายเลขบัญชี;
  private double balance; // ยอดเงินคงเหลือ;

  public BankAccount(String newID) {
    id = newID;
  }
  public String getID() {
    return id;
  }
  public double getBalance() {
    return balance;
  }
  public void deposit(double amt) {
    if (amt < 0) throw new IllegalArgumentException("amt<0:"+amt);
    balance += amt;
  }
  public void withdraw(double amt) {
    if (amt < 0) throw new IllegalArgumentException("amt<0:"+amt);
    if (amt > balance) throw new IllegalArgumentException("ไม่พอ");
    balance -= amt;
  }
  public void transferTo(BankAccount to, double amt) {
    withdraw(amt);
    to.deposit(amt);
  }
}