1 package com.test.zj;
 2
 3 public class PolyConstructors {
 4
 5     public static void main(String[] args) {
 6         // TODO Auto-generated method stub
 7         new RoundGlyph(5);
 8     }
 9
10 }
11
12 class RoundGlyph extends Glyph {
13     private int radius = 1;
14
15     public RoundGlyph(int r) {
16         // TODO Auto-generated constructor stub
17         radius = r;
18         System.out.println("RoundGlyph radius==" + radius);
19     }
20
21     @Override
22     void draw() {
23         // TODO Auto-generated method stub
24         System.out.println("RoundGlyph draw() radius==" + radius);
25     }
26
27 }
28
29 class Glyph {
30     void draw() {
31         System.out.println("print glyph.draw()");
32     }
33
34     Glyph() {
35         System.out.println("Glyph() before draw()");
36         draw();
37         System.out.println("Glyph() after draw()");
38
39     }
40
41 }

1 Glyph() before draw()
2 RoundGlyph draw() radius==1
3 Glyph() after draw()
4 RoundGlyph radius==5

 1 package com.test.zj;
 2
 3 public class SuperClass
 4 {
 5     private int superValue;
 6
 7     public SuperClass()
 8     {
 9         setSuperValue(100);
10
11     }
12
13     public void setSuperValue(int x)
14     {
15         superValue=x;
16     }
17
18 }

 1 //这个子类继承自父类superclass
 2 public class SubClass extends SuperClass
 3 {
 4     private int subValue=10;
 5
 6     public SubClass()
 7     {
 8
 9     }
10     //这个方法重写了父类的方法
11     public void setSuperValue(int x)
12     {
13         //先调用父类的方法
14         super.setSuperValue(x);
15         //然后把值赋给自己的变量
16         subValue=x;
17
18     }
19
20     public void printSubValue()
21     {
22         System.out.println("subclass subvalue=="+subValue);
23     }
24
25 }

 1 package com.test.zj;
 2
 3 public class MainClass {
 4
 5     public static void main(String[] args) {
 6         // TODO Auto-generated method stub
 7         SubClass sc=new SubClass();
 8         sc.printSubValue();
 9     }
10
11 }