update:demo7

com/study/demo7/BankWithdraw.java

@@ -0,0 +1,37 @@
+package com.study.demo7;
+
+// 自定义异常
+class InsufficientBalanceException extends Exception {
+  public InsufficientBalanceException(String message) {
+    super(message);
+  }
+}
+
+// 账户类
+class Account {
+  private double balance;
+
+  public Account(double balance) {
+    this.balance = balance;
+  }
+
+  public void withdraw(double amount) throws InsufficientBalanceException {
+    if (amount > balance) {
+      throw new InsufficientBalanceException("余额不足，当前余额: " + balance);
+    }
+    balance -= amount;
+    System.out.println("取款成功，剩余余额: " + balance);
+  }
+}
+
+// 主类
+public class BankWithdraw {
+  public static void main(String[] args) {
+    Account account = new Account(1000.0);
+    try {
+      account.withdraw(100.0);
+    } catch (InsufficientBalanceException e) {
+      System.out.println("取款失败: " + e.getMessage());
+    }
+  }
+}