package com.study.demo9; public class Outer { public static void main(String[] args) { Account account = new Account("张三", 1000.0); System.out.println("Can pay 500: " + account.canPay(500)); System.out.println("Can pay 1500: " + account.canPay(1500)); } } class Account { private String ownerName; private double balance; public Account(String ownerName, double balance) { this.ownerName = ownerName; this.balance = balance; } public boolean canPay(double amount) { SecurityChecker checker = new SecurityChecker(); return checker.checkBalance(amount); } class SecurityChecker { boolean checkBalance(double amount) { return balance >= amount; } } }