动手动脑（10.22）

package org.yuan.my_project;

class Grandparent 
{
    public Grandparent()
     {
            System.out.println("GrandParent Created.");
}
    public Grandparent(String string) 
    {
            System.out.println("GrandParent Created.String:" + string);
 }
}
class Parent extends Grandparent
{
    public Parent()
     {
            //super("Hello.Grandparent.");
            System.out.println("Parent Created");    
            //super("Hello.Grandparent.");
      }
}
class Child extends Parent 
{
    public Child()
     {    
        System.out.println("Child Created");
      }
}
public class TestInherits {
    public static void main(String args[])
     {
        Child c=new Child();
        //System.out.println(c);
 }
}

package org.yuan.my_project;
class Base {
    void method() { 
            System.out.println("base");
    }
   
}
class Sub extends Base {
    void method() { 
            //super.method();
            System.out.println("Sub");
    }
   
}
public class Test {
    public static void main(String[] args) {
            Base sub1 = new Sub(); 
            sub1.method();
           
            Sub sub2 = new Sub();
            sub2.method(); 
    }
}

public class ParentChildTest {
    public static void main(String[] args) {
        Parent parent=new Parent();
        parent.printValue();
        Child child=new Child();
        child.printValue();
        
        parent=child;
        parent.printValue();
        
        parent.myValue++;
        parent.printValue();
        
        ((Child)parent).myValue++;
        parent.printValue();
        
    }
}
class Parent{
    public int myValue=100;
    public void printValue() {
        System.out.println("Parent.printValue(),myValue="+myValue);
    }
}
class Child extends Parent{
    public int myValue=200;
    public void printValue() {
        System.out.println("Child.printValue(),myValue="+myValue);
    }
}