定义一个类实现银行账户的概念。包括的属性有“账号”和“存款余额”，包括的方法有“存款”、“取款”、“查询余额”和“显示账号”。编写一测试类，创建两个不同的账户类的对象，并分别完成存款、取款、查询余额、显示账号等操作。
public class BankAccount {
String account ;
int account_num;
//构造函数
public BankAccount(String account,int account_num){
this.account=account;
this.account_num=account_num;
}
//存钱
public String addNum(int num){
account_num= account_num+num;
return "存钱成功";
}
//取钱
public String getNum(int num){
String result;
if(account_num>num){
account_num =account_num-num;
result="取钱成功";
}else{
result="账户余额不足，还剩"+account_num;
}
return result;
}//显示余额
public String displayNum(){
return "账户余额："+account_num;
}//显示账号
public String displayAccount(){
return "账户："+account;
}
public static void main(String[] args){
BankAccount Tom = new BankAccount("Tom",100);
BankAccount jane = new BankAccount("jane",50); //显示他们各自的余额
System.out.println("===显示各自的余额===");
System.out.println("Tom:"+Tom.displayNum());
System.out.println("jane:"+jane.displayNum()); //存钱取钱
System.out.println("===存钱取钱===");
System.out.println("Tom取50:"+Tom.getNum(50));
System.out.println("jane存200:"+jane.addNum(200)); //显示账户 显示余额
System.out.println("===存钱取钱===");
System.out.println(Tom.displayAccount()+""+Tom.displayNum());
System.out.println(jane.displayAccount()+""+jane.displayNum());
}
}