问题
This question already has an answer here:
- Java overloading and overriding 9 answers
- Java overloading and overriding 9 answers
What is the difference between overloading a method and overriding a method? Can anyone explain it with an example?
回答1:
Method overloading deals with the notion of having two or more methods in the same class with the same name but different arguments.
void foo(int a)
void foo(int a, float b)
Method overriding means having two methods with the same arguments, but different implementations. One of them would exist in the parent class, while another will be in the derived, or child class. The @Override annotation, while not required, can be helpful to enforce proper overriding of a method at compile time.
class Parent {
void foo(double d) {
// do something
}
}
class Child extends Parent {
@Override
void foo(double d){
// this method is overridden.
}
}
回答2:
Method overriding is when a child class redefines the same method as a parent class, with the same parameters. For example, the standard Java class java.util.LinkedHashSet extends java.util.HashSet. The method add() is overridden in LinkedHashSet. If you have a variable that is of type HashSet, and you call its add() method, it will call the appropriate implementation of add(), based on whether it is a HashSet or a LinkedHashSet. This is called polymorphism.
Method overloading is defining several methods in the same class, that accept different numbers and types of parameters. In this case, the actual method called is decided at compile-time, based on the number and types of arguments. For instance, the method System.out.println() is overloaded, so that you can pass ints as well as Strings, and it will call a different version of the method.
来源：https://stackoverflow.com/questions/12374399/what-is-the-difference-between-method-overloading-and-overriding