添加 w5 继承与多态练习

w5/DrawCircle.java

@@ -0,0 +1,6 @@
+public class DrawCircle extends DrawShape {
+    @Override
+    public void draw() {
+        System.out.println("绘制圆形 O");
+    }
+}

w5/DrawRectangle.java

@@ -0,0 +1,6 @@
+public class DrawRectangle extends DrawShape {
+    @Override
+    public void draw() {
+        System.out.println("绘制矩形 □");
+    }
+}

w5/DrawShape.java

@@ -0,0 +1,5 @@
+public class DrawShape {
+    public void draw() {
+        System.out.println("绘制形状");
+    }
+}

w5/ShapeTest.java

@@ -0,0 +1,13 @@
+public class ShapeTest {
+    public static void drawShape(DrawShape s) {
+        s.draw();
+    }
+
+    public static void main(String[] args) {
+        DrawShape circle = new DrawCircle();
+        DrawShape rectangle = new DrawRectangle();
+
+        drawShape(circle);
+        drawShape(rectangle);
+    }
+}