class Person{

private String name="Person";

int age=0;

}

public class Child extends Person{

public String grade;

public static void main(String[] args){

Person p = new Child();

System.out.println(p.name);

}

}

class Person{

public Person(){

System.out.println("this is a Person");

}

}

public class Teacher extends Person{

private String name="tom";

public Teacher(){

System.out.println("this is a teacher");

super();

}

public static void main(String[] args){

Teacher teacher = new Teacher();

System.out.println(this.name);

}

}

class Book{

protected int getPrice(){

return 30;

}

}

public class ComputerBook extends Book{

}

interface IDemo{

public static final String name ;// 第1行

void print() ;// 第2行

public void getInfo() ;// 第3行

}

abstract class Person implements IDemo{ //第4行

public void print(){

}

}

public class Test extends Father{

private String name="test";

public static void main(String[] args){

Test test = new Test();

System.out.println(test.getName());

}

}

class Father{

private String name="father";

public String getName() {

return name;

}

}