Java super关键字调用父类的方法疑惑

 1 public class PhoneBill extends Bill {
 2     @Override
 3     public void foo1(){
 4         System.out.println("PhoneBill:foo1");
 5     }
 6     @Override
 7     public void foo2(){
 8         System.out.println("PhoneBill:foo2");
 9         super.foo2();
10     }
11 }

1 public class Bill {
2     public void foo1(){
3         System.out.println("Bill:foo1");
4     }
5     public void foo2(){
6         this.foo1();
7         System.out.println("Bill:foo2");
8     }
9 }

1 public class test {
2 
3     public static void main(String[] args) {
4         // TODO Auto-generated method stub
5         PhoneBill phone = new PhoneBill();
6         phone.foo2();
7     }
8 }

PhoneBill:foo2
PhoneBill:foo1
Bill:foo2