Java/com/study/demo2/Account.java

package com.study.demo2;

public class Account {
  private String accountId;
  private String owner;
  private double balance;

  public Account(String accountId, String owner, double balance) {
    this.accountId = accountId;
    this.owner = owner;
    this.balance = balance;
  }

  public void deposit(double amount) {
    if (amount > 0) {
      balance += amount;
    }
  }

  public void withdraw(double amount) {
    if (amount > 0 && amount <= balance) {
      balance -= amount;
    }
  }

  public void transfer(Account target, double amount) {
    if (amount > 0 && amount <= balance) {
      this.balance -= amount;
      target.balance += amount;
    }
  }

  public double getBalance() {
    return balance;
  }
}