建立Bank類，類中有變量double balance表示存款,Bank類的構造方法能初始化余額，Bank類中有存款的方法cunKuan(double balance)，取款的發方法withDrawal(double dAmount),當取款的數額大於存款時,拋出InsufficientFundsException,取款數額為負數，拋出NagativeFundsException,當用方法withdrawal(150)，withdrawal(-15)時會拋出自定義異常。
1 public class Bank {
2 double yu_e;
3 double balance;
4
5 Bank(double yu_e) {
6 this.yu_e = yu_e;
7 System.out.println("賬戶內余額："+this.yu_e+"元");
8 }
9
10 void cunKuan(double balance) throws Exception {
11 if(balance<0){
12 throw new Exception("存款不能為負");
13 }
14 yu_e += balance;
15 }
16
17 void withDrawal(double dAmount) throws Exception {
18 if(dAmount>yu_e){
19 throw new Exception("InsufficientFundsException，余額不足");
20 }else if (dAmount<0){
21 throw new Exception("NagativeFundsException,取款值為負");
22 }
23 yu_e -= dAmount;
24 }
25
26 public static void main(String[] args) {
27
28 Bank b = new Bank(10);
29 try {
30 b.cunKuan(-100);
31 } catch (Exception e) {
32 e.printStackTrace();
33 }
34
35 try {
36 b.withDrawal(150);
37 } catch (Exception e) {
38 e.printStackTrace();
39 }
40
41 try {
42 b.withDrawal(-15);
43 } catch (Exception e) {
44 e.printStackTrace();
45 }
46
47 System.out.println("存款余額"+b.yu_e+"元");
48
49 }
50
51 }
運行：
