public class Account { String zhanghu; double cunkuanyue; //先初始化 Account(String zhanghu,double cunkuanyue) { this.zhanghu=zhanghu; this.cunkuanyue=cunkuanyue; } //存款 double cunkuan(double qianshu) { if(qianshu<0) { System.out.println("钱数错误"); } else { System.out.println("您存了"+qianshu); this.cunkuanyue+=qianshu; } return this.cunkuanyue; } /* void cunkuan(double qianshu) { //验证 if(qianshu<0) { System.out.println("钱数错误"); return; } System.out.println("我存了"+qianshu); this.cunkuanyue+=qianshu; } */ //取款 void qukuan(double qianshu) { if(qianshu>this.cunkuanyue) { System.out.println("余额不足"); return; } System.out.println("我取了"+qianshu); this.cunkuanyue-=qianshu; } //查询余额 double getyue() { return this.cunkuanyue; } public static void main(String[] args) { Account a=new Account("123456",1000); a.cunkuan(100); System.out.println("查询余额="+a.getyue()); a.qukuan(200); System.out.println("查询余额= "+a.getyue()); } }