diff --git a/design-pattern/gof/src/visitor/after/Circle.java b/design-pattern/gof/src/visitor/after/Circle.java
new file mode 100644
index 00000000..4549c27f
--- /dev/null
+++ b/design-pattern/gof/src/visitor/after/Circle.java
@@ -0,0 +1,9 @@
+package visitor.after;
+
+public class Circle implements Shape {
+
+    @Override
+    public void accept(Device device) {
+        device.print(this);
+    }
+}
diff --git a/design-pattern/gof/src/visitor/after/Client.java b/design-pattern/gof/src/visitor/after/Client.java
new file mode 100644
index 00000000..ed767ddb
--- /dev/null
+++ b/design-pattern/gof/src/visitor/after/Client.java
@@ -0,0 +1,10 @@
+package visitor.after;
+
+public class Client {
+
+    public static void main(String[] args) {
+        Shape rectangle = new Rectangle();
+        Device device = new Pad();
+        rectangle.accept(device);
+    }
+}
diff --git a/design-pattern/gof/src/visitor/after/Device.java b/design-pattern/gof/src/visitor/after/Device.java
new file mode 100644
index 00000000..10d96932
--- /dev/null
+++ b/design-pattern/gof/src/visitor/after/Device.java
@@ -0,0 +1,9 @@
+package visitor.after;
+
+public interface Device {
+    void print(Circle circle);
+
+    void print(Rectangle rectangle);
+
+    void print(Triangle triangle);
+}
diff --git a/design-pattern/gof/src/visitor/after/Pad.java b/design-pattern/gof/src/visitor/after/Pad.java
new file mode 100644
index 00000000..dd075c7b
--- /dev/null
+++ b/design-pattern/gof/src/visitor/after/Pad.java
@@ -0,0 +1,18 @@
+package visitor.after;
+
+public class Pad implements Device {
+    @Override
+    public void print(Circle circle) {
+        System.out.println("Print Circle to Pad");
+    }
+
+    @Override
+    public void print(Rectangle rectangle) {
+        System.out.println("Print Rectangle to Pad");
+    }
+
+    @Override
+    public void print(Triangle triangle) {
+        System.out.println("Print Triangle to Pad");
+    }
+}
diff --git a/design-pattern/gof/src/visitor/after/Phone.java b/design-pattern/gof/src/visitor/after/Phone.java
new file mode 100644
index 00000000..261f5a41
--- /dev/null
+++ b/design-pattern/gof/src/visitor/after/Phone.java
@@ -0,0 +1,18 @@
+package visitor.after;
+
+public class Phone implements Device {
+    @Override
+    public void print(Circle circle) {
+        System.out.println("Print Circle to Phone");
+    }
+
+    @Override
+    public void print(Rectangle rectangle) {
+        System.out.println("Print Rectangle to Phone");
+    }
+
+    @Override
+    public void print(Triangle triangle) {
+        System.out.println("Print Triangle to Phone");
+    }
+}
diff --git a/design-pattern/gof/src/visitor/after/Rectangle.java b/design-pattern/gof/src/visitor/after/Rectangle.java
new file mode 100644
index 00000000..4c8abede
--- /dev/null
+++ b/design-pattern/gof/src/visitor/after/Rectangle.java
@@ -0,0 +1,9 @@
+package visitor.after;
+
+public class Rectangle implements Shape {
+
+    @Override
+    public void accept(Device device) {
+        device.print(this);
+    }
+}
diff --git a/design-pattern/gof/src/visitor/after/Shape.java b/design-pattern/gof/src/visitor/after/Shape.java
new file mode 100644
index 00000000..89203bbb
--- /dev/null
+++ b/design-pattern/gof/src/visitor/after/Shape.java
@@ -0,0 +1,7 @@
+package visitor.after;
+
+public interface Shape {
+
+    void accept(Device device);
+
+}
diff --git a/design-pattern/gof/src/visitor/after/Triangle.java b/design-pattern/gof/src/visitor/after/Triangle.java
new file mode 100644
index 00000000..dfd0e6e7
--- /dev/null
+++ b/design-pattern/gof/src/visitor/after/Triangle.java
@@ -0,0 +1,9 @@
+package visitor.after;
+
+public class Triangle implements Shape {
+
+    @Override
+    public void accept(Device device) {
+        device.print(this);
+    }
+}
diff --git a/design-pattern/gof/src/visitor/after/Watch.java b/design-pattern/gof/src/visitor/after/Watch.java
new file mode 100644
index 00000000..0ab7d137
--- /dev/null
+++ b/design-pattern/gof/src/visitor/after/Watch.java
@@ -0,0 +1,18 @@
+package visitor.after;
+
+public class Watch implements Device {
+    @Override
+    public void print(Circle circle) {
+        System.out.println("Print Circle to Watch");
+    }
+
+    @Override
+    public void print(Rectangle rectangle) {
+        System.out.println("Print Rectangle to Watch");
+    }
+
+    @Override
+    public void print(Triangle triangle) {
+        System.out.println("Print Triangle to Watch");
+    }
+}
diff --git a/design-pattern/gof/src/visitor/before/Circle.java b/design-pattern/gof/src/visitor/before/Circle.java
new file mode 100644
index 00000000..cffd0049
--- /dev/null
+++ b/design-pattern/gof/src/visitor/before/Circle.java
@@ -0,0 +1,12 @@
+package visitor.before;
+
+public class Circle implements Shape {
+    @Override
+    public void printTo(Device device) {
+        if (device instanceof Phone) {
+            System.out.println("print Circle to phone");
+        } else if (device instanceof Watch) {
+            System.out.println("print Circle to watch");
+        }
+    }
+}
diff --git a/design-pattern/gof/src/visitor/before/Client.java b/design-pattern/gof/src/visitor/before/Client.java
new file mode 100644
index 00000000..2e410544
--- /dev/null
+++ b/design-pattern/gof/src/visitor/before/Client.java
@@ -0,0 +1,10 @@
+package visitor.before;
+
+public class Client {
+
+    public static void main(String[] args) {
+        Shape rectangle = new Rectangle();
+        Device device = new Phone();
+        rectangle.printTo(device);
+    }
+}
diff --git a/design-pattern/gof/src/visitor/before/Device.java b/design-pattern/gof/src/visitor/before/Device.java
new file mode 100644
index 00000000..68c49c6d
--- /dev/null
+++ b/design-pattern/gof/src/visitor/before/Device.java
@@ -0,0 +1,4 @@
+package visitor.before;
+
+public interface Device {
+}
diff --git a/design-pattern/gof/src/visitor/before/Phone.java b/design-pattern/gof/src/visitor/before/Phone.java
new file mode 100644
index 00000000..f0cbced1
--- /dev/null
+++ b/design-pattern/gof/src/visitor/before/Phone.java
@@ -0,0 +1,4 @@
+package visitor.before;
+
+public class Phone implements Device{
+}
diff --git a/design-pattern/gof/src/visitor/before/Rectangle.java b/design-pattern/gof/src/visitor/before/Rectangle.java
new file mode 100644
index 00000000..83f5c0e6
--- /dev/null
+++ b/design-pattern/gof/src/visitor/before/Rectangle.java
@@ -0,0 +1,13 @@
+package visitor.before;
+
+public class Rectangle implements Shape {
+
+    @Override
+    public void printTo(Device device) {
+        if (device instanceof Phone) {
+            System.out.println("print Rectangle to phone");
+        } else if (device instanceof Watch) {
+            System.out.println("print Rectangle to watch");
+        }
+    }
+}
diff --git a/design-pattern/gof/src/visitor/before/Shape.java b/design-pattern/gof/src/visitor/before/Shape.java
new file mode 100644
index 00000000..e1a11a35
--- /dev/null
+++ b/design-pattern/gof/src/visitor/before/Shape.java
@@ -0,0 +1,7 @@
+package visitor.before;
+
+public interface Shape {
+
+    void printTo(Device device);
+
+}
diff --git a/design-pattern/gof/src/visitor/before/Triangle.java b/design-pattern/gof/src/visitor/before/Triangle.java
new file mode 100644
index 00000000..e93ea055
--- /dev/null
+++ b/design-pattern/gof/src/visitor/before/Triangle.java
@@ -0,0 +1,14 @@
+package visitor.before;
+
+public class Triangle implements Shape {
+
+    @Override
+    public void printTo(Device device) {
+        if (device instanceof Phone) {
+            System.out.println("print Triangle to Phone");
+        } else if (device instanceof Watch) {
+            System.out.println("print Triangle to Watch");
+        }
+    }
+
+}
diff --git a/design-pattern/gof/src/visitor/before/Watch.java b/design-pattern/gof/src/visitor/before/Watch.java
new file mode 100644
index 00000000..6145c032
--- /dev/null
+++ b/design-pattern/gof/src/visitor/before/Watch.java
@@ -0,0 +1,4 @@
+package visitor.before;
+
+public class Watch implements Device{
+}