diff --git a/w3/BankAccount.java b/w3/BankAccount.java
new file mode 100644
index 0000000..d1cbf1b
--- /dev/null
+++ b/w3/BankAccount.java
@@ -0,0 +1,50 @@
+public class BankAccount {
+	private final int accountNumber;
+	private String ownerName;
+	private double balance;
+
+	public BankAccount(int accountNumber,String ownerName){
+		this.balance=0.0;
+		this.accountNumber=accountNumber;
+		this.ownerName=ownerName;
+	}
+
+	public void setOwnername(String ownerName) {
+		this.ownerName=ownerName;
+	}
+
+	public void addBalance(double add){
+
+		if (add > 0.0){
+			this.balance+=add;
+			System.out.println("成功更新余额为"+balance+"元");
+		} else {
+			System.out.println("存款失败，金额小于零");
+		}
+	}
+
+	public void takeBalance(double take){
+		if (take > 0.0 && take <=balance){
+			this.balance-=take;
+			System.out.println("成功更新余额为"+balance+"元");
+		} else {
+			System.out.println("取款失败，金额不足");
+		}
+	}
+	public void lookBalance(){
+		System.out.println("余额为"+balance);
+	}
+    public static void main(String[] args) {
+        BankAccount myAccount = new BankAccount(1001, "张三");
+        
+        myAccount.lookBalance(); // 输出: 余额为 0.0
+        
+        myAccount.addBalance(500.0); // 输出: 成功存入... 余额 500.0
+        
+        myAccount.takeBalance(200.0); // 输出: 成功取出... 余额 300.0
+        
+        myAccount.takeBalance(400.0); // 输出: 取款失败... (余额不足)
+        
+        myAccount.addBalance(-50.0);  // 输出: 存款失败... (金额小于零)
+    }
+}
\ No newline at end of file