diff --git a/src/class18/Test.java b/src/class18/Test.java
new file mode 100644
index 0000000..bf1000b
--- /dev/null
+++ b/src/class18/Test.java
@@ -0,0 +1,25 @@
+package class18;
+
+public class Test {
+    public static void main(String[] args) {
+        C c = new C();
+        System.out.println(c.a);
+        System.out.println(c.b);
+        c.m1();
+    }
+}
+class A{
+    int a = 10;
+
+    void m1(){
+        System.out.println(a);
+    }
+}
+
+class B extends A{
+    int b = 30;
+}
+
+class C extends B{
+    int a = 30;
+}
diff --git a/src/class18/Test2.java b/src/class18/Test2.java
new file mode 100644
index 0000000..f3aef97
--- /dev/null
+++ b/src/class18/Test2.java
@@ -0,0 +1,20 @@
+package class18;
+
+public class Test2 {
+    public static void main(String[] args) {
+        Zi z = new Zi();
+        z.print();
+    }
+}
+class Fu{
+    String name = "fu的name";
+}
+class Zi extends Fu{
+    String name = "zi的name";
+    public void print(){
+        String name = "局部变量";
+        System.out.println(name); // 局部变量
+        System.out.println(this.name); // zi的name
+        System.out.println(super.name); // fu的name
+    }
+}
diff --git a/src/class19/Test.java b/src/class19/Test.java
new file mode 100644
index 0000000..f9e6db1
--- /dev/null
+++ b/src/class19/Test.java
@@ -0,0 +1,22 @@
+package class19;
+
+public class Test {
+    public static void main(String[] args) {
+        Cat c = new Cat();
+        c.cry();
+
+    }
+}
+class Cat extends  Animal{
+    @Override //方法重写的校验注解，会校验与被重写方法的形参和返回值类型是否一致，保证方法重写安全
+    public void cry() {
+        System.out.println("喵喵喵~~~");
+    }
+}
+
+class Animal{
+    public void cry(){
+        System.out.println("动物会叫~~~");
+    }
+
+}