首页 > 代码库 > 归档七

归档七

课后作业1

运行 TestInherits.java ,观察输出,总结父类与子类之间构造方法的调用关系修改Parent构造方法的代码,调用GrandParent的另一个构造函数

 

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 statclass 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();

    }

}

 

ic void main(String args[]) {

        Child c = new Child();

    }

}

结论:

    通过 super 调用基类构造方法,必须是子类构造方法中的第一个语句。子类中,调用父类中被覆盖的方法,可以使用super语句

课后作业2

代码:

        class Parent{

 

    public Parent() {

       

        System.out.println("Parent Created");

 

    }

    public void show(){

      System.out.println("hello java !");

    }

}

 

class Child extends Parent {

 

    public Child(){

        System.out.println("Child Created");

}

    public void show(){

        super.show();

     System.out.println("say hello! child!!!");

     

   }

}

 

public class Test6 {

 

    public static void main(String args[]) {

        Child c = new Child();

        c.show();

    }

}

归档七