2、定义一个银行账户类，该类的属性有：账户、存款余额；方法有：存款、取款、查询；定义一个描述取款数目超出余额的异常，在取款方法中抛出该异常。

import java.util.*;
class MyException1 extends Exception{
    String xinxi;
    MyException1(int m){
        xinxi="余额不足！";
    }
    public String toString(){
        return xinxi;
    }
}
class bank{
    int amount;//账户
    int yue=2000;//余额
    public void cunkuan(int m){
        yue=yue+m;
        System.out.println(yue);
    }
    public void qukuan(int m) throws MyException1 {
        if (m>yue){
            MyException1 exception=new MyException1(m);
            throw exception;
        }
        yue=yue-m;
    }
    public int chaxun(){
        return yue;
    }
}
public class Test1 {
    public static void main(String args[]){
        Scanner input=new Scanner(System.in);
        System.out.println("请输入1（存款）；2（取款）；3（查询）");
        System.out.println("请输入金额！");
        int a=input.nextInt();
        int c=input.nextInt();
        bank b=new bank();
        try {
            switch (a){
                case 1: b.cunkuan(c);
                case 2: b.qukuan(c);
                case 3: b.chaxun();
            }
        }catch(MyException1 e){
            System.out.println(e.toString());
        }
    }
}