## 参数列表
与被重写方法的参数列表必须完全相同
```java
class AnimalShelter {
public Animal getAnimals(Animal animal) {
return null;
}
}
class DogShelter extends AnimalShelter {
@Override
public Dog getAnimals(Dog dog) {
return null;
}
}
```
会出现`Method does not override method from its superclass` 的编译错误，
因为与父类或接口中的参数列表完全一致，是**一模一样**的意思，就算参数之间是父子类也不行！
## 返回类型
与被重写方法的返回类型可以不相同，但是必须是父类返回值的派生类
下面这样是 OK 的
```java
class AnimalShelter {
public Animal getAnimals() {
return null;
}
}
class DogShelter extends AnimalShelter {
@Override
public Dog getAnimals() {
return null;
}
}
```
由于数组可以[协变](协变.md)，下面这样也是 ok 的
```java
class Animal {}
class Dog extends Animal {}
class AnimalShelter {
public Animal[] getAnimals() {
return new Animal[10];
}
}
class DogShelter extends AnimalShelter {
@Override
public Dog[] getAnimals() {
return new Dog[10];
}
}
```
```Java
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```