添加 w7 自定义异常与银行取款练习

w7/BankWithdrawalTest.java

@@ -0,0 +1,66 @@
+public class BankWithdrawalTest {
+
+    static class InsufficientFundsException extends Exception {
+        private double balance;
+
+        public InsufficientFundsException(double balance) {
+            super("余额不足，当前余额：" + balance + " 元");
+            this.balance = balance;
+        }
+
+        public double getBalance() {
+            return balance;
+        }
+    }
+
+    static class Account {
+        private double balance;
+
+        public Account(double initialBalance) {
+            this.balance = initialBalance;
+        }
+
+        public void withdraw(double amount) throws InsufficientFundsException {
+            if (amount <= 0) {
+                throw new IllegalArgumentException("取款金额必须大于0");
+            }
+            if (amount > balance) {
+                throw new InsufficientFundsException(balance);
+            }
+            balance -= amount;
+            System.out.println("取款成功！取出：" + amount + " 元，剩余余额：" + balance + " 元");
+        }
+
+        public double getBalance() {
+            return balance;
+        }
+    }
+
+    public static void main(String[] args) {
+        Account myAccount = new Account(1000.0);
+
+        System.out.println("--- 测试1：正常取款 ---");
+        try {
+            myAccount.withdraw(300);
+        } catch (InsufficientFundsException e) {
+            System.out.println("错误：" + e.getMessage());
+        }
+
+        System.out.println("\n--- 测试2：余额不足取款 ---");
+        try {
+            myAccount.withdraw(800);
+        } catch (InsufficientFundsException e) {
+            System.out.println("取款失败：" + e.getMessage());
+            System.out.println("提示：请检查取款金额，当前账户余额为 " + e.getBalance() + " 元");
+        }
+
+        System.out.println("\n--- 测试3：非法金额取款 ---");
+        try {
+            myAccount.withdraw(-50);
+        } catch (IllegalArgumentException e) {
+            System.out.println("错误：" + e.getMessage());
+        } catch (InsufficientFundsException e) {
+            System.out.println("取款失败：" + e.getMessage());
+        }
+    }
+}