java 子类与父类继承关系

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People.java

public class People {

    int age,leg = 2,hand = 2;

    protected void showPeopleMess() {

       System.out.printf("%d岁，%d只脚,%d只手\t",age,leg,hand);

    }

}

Student.java

public class Student extends People {

   int number;

   void tellNumber() {

       System.out.printf("学号:%d\t",number);

   }

   int add(int x,int y) {

      return x+y;

   }

}

UniverStudent.java

public class UniverStudent extends Student {

   int multi(int x,int y) {

      return x*y;

   }

}

Example5_1.java

public class Example5_1 {

   public static void main(String args[]) {

      Student zhang = new Student();

      zhang.age = 17;           //访问继承的成员变量

      zhang.number=100101;

      zhang.showPeopleMess();  //调用继承的方法

      zhang.tellNumber();

      int x=9,y=29;

      System.out.print("会做加法:");

      int result=zhang.add(x,y);

      System.out.printf("%d+%d=%d\n",x,y,result);

      UniverStudent geng = new UniverStudent();

      geng.age = 21;          //访问继承的成员变量

      geng.number=6609;

      geng.showPeopleMess();  //调用继承的方法

      geng.tellNumber();        //调用继承的方法

      System.out.print("会做加法:");

      result=geng.add(x,y);      //调用继承的方法

      System.out.printf("%d+%d=%d\t",x,y,result);

      System.out.print("会做乘法:");

      result=geng.multi(x,y);

      System.out.printf("%d×%d=%d\n",x,y,result);

   }

}