java 继承

public class People{
private int age;
public void setAge(int age){
this.age=age;
}
public int getAge(){
return age;
}
public void show(){
System.out.print("i am a people");
}

}

public class Teacher extends People{
private int teachernumber;
public void setTeacherNumber(int teachernumber){
this.teachernumber=teachernumber;
}
public int getTeacherNumbert(){
return teachernumber;
}
public void show(){
System.out.print("i am a Teacher");
}
public void printTeacherNumber(){
System.out.println(teachernumber);
}
public void printAge(){
System.out.println(getAge());
}
}

public class Example2{
public static void main(String args[]){
Teacher t1=new Teacher();
t1.setTeacherNumber(11);
t1.setAge(23);
t1.printTeacherNumber();
t1.printAge();
t1.show();
} 
}