update:demo9

com/study/demo9/Outer.java

@@ -0,0 +1,30 @@
+package com.study.demo9;
+
+public class Outer {
+    public static void main(String[] args) {
+        Account account = new Account("张三", 1000.0);
+        System.out.println("Can pay 500: " + account.canPay(500));
+        System.out.println("Can pay 1500: " + account.canPay(1500));
+    }
+}
+
+class Account {
+    private String ownerName;
+    private double balance;
+
+    public Account(String ownerName, double balance) {
+        this.ownerName = ownerName;
+        this.balance = balance;
+    }
+
+    public boolean canPay(double amount) {
+        SecurityChecker checker = new SecurityChecker();
+        return checker.checkBalance(amount);
+    }
+
+    class SecurityChecker {
+        boolean checkBalance(double amount) {
+            return balance >= amount;
+        }
+    }
+}

com/study/demo9/PermissionSystem.java

@@ -0,0 +1,40 @@
+package com.study.demo9;
+
+
+public class PermissionSystem {
+    public static void main(String[] args) {
+        User admin = new User("admin", "admin");
+        User guest = new User("guest", "guest");
+
+        System.out.println("Admin can delete: " + admin.checkPermission("delete"));
+        System.out.println("Admin can read: " + admin.checkPermission("read"));
+        System.out.println("Guest can read: " + guest.checkPermission("read"));
+        System.out.println("Guest can delete: " + guest.checkPermission("delete"));
+    }
+}
+
+class User {
+    private String username;
+    private String role;
+
+    public User(String username, String role) {
+        this.username = username;
+        this.role = role;
+    }
+
+    public boolean checkPermission(String operation) {
+        PermissionChecker checker = new PermissionChecker();
+        return checker.hasPermission(operation);
+    }
+
+    class PermissionChecker {
+        boolean hasPermission(String operation) {
+            if ("admin".equals(role)) {
+                return true;
+            } else if ("guest".equals(role)) {
+                return "read".equals(operation);
+            }
+            return false;
+        }
+    }
+}

com/study/demo9/TaskRunner.java

@@ -0,0 +1,19 @@
+package com.study.demo9;
+
+public class TaskRunner {
+    public void runTask() {
+        class LocalTask {
+            void execute() {
+                System.out.println("正在执行临时任务");
+            }
+        }
+
+        LocalTask task = new LocalTask();
+        task.execute();
+    }
+
+    public static void main(String[] args) {
+        TaskRunner runner = new TaskRunner();
+        runner.runTask();
+    }
+}