feat: 完成W3 BankAccount.java标准源文件提交

W3/BankAccount.java.txt

@@ -0,0 +1,50 @@
+public class BankAccount {
+    // private 成员变量（封装：私有化属性）
+    private String accountNumber;
+    private String ownerName;
+    private double balance;
+
+    // 构造方法：初始化账户
+    public BankAccount(String accountNumber, String ownerName) {
+        this.accountNumber = accountNumber;
+        this.ownerName = ownerName;
+        this.balance = 0.0;
+    }
+
+    // getter 和 setter 方法（封装：提供公共访问接口）
+    public String getAccountNumber() {
+        return accountNumber;
+    }
+
+    public String getOwnerName() {
+        return ownerName;
+    }
+
+    public void setOwnerName(String ownerName) {
+        this.ownerName = ownerName;
+    }
+
+    public double getBalance() {
+        return balance;
+    }
+
+    // 业务方法：存款
+    public void deposit(double amount) {
+        if (amount > 0) {
+            balance += amount;
+            System.out.println("存款成功，当前余额：" + balance);
+        } else {
+            System.out.println("存款金额必须大于0");
+        }
+    }
+
+    // 业务方法：取款
+    public void withdraw(double amount) {
+        if (amount > 0 && amount <= balance) {
+            balance -= amount;
+            System.out.println("取款成功，当前余额：" + balance);
+        } else {
+            System.out.println("余额不足或金额无效");
+        }
+    }
+}