A detailed explanation of method rewriting in JAVA and how it differs from overloading

1. What is method overriding?

(1) Polymorphism between parent class and subclass, redefining the functions of the parent class. If a method defined in a subclass has the same name and parameters as its parent class, we say the method is overriding. In Java, a subclass can inherit methods from a parent class without rewriting the same methods.

But sometimes the subclass does not want to inherit the method of the parent class unchanged, but wants to make certain modifications, which requires method rewriting.

Method overriding is also called method overwriting.

(2) If a method in the subclass has the same method name, return type, and parameter list as a method in the parent class, the new method will overwrite the original method.

If you need the original method in the parent class, you can use the super keyword, which refers to the parent class of the current class.

(3) The access modification rights of subclass functions cannot be less than those of the parent class;
The following is an example of rewriting:

Concept: the mechanism for calling object methods.

2. Rules for overriding methods

1. The parameter list must be completely the same as the overridden method, otherwise it cannot be called overriding. It's overloaded.

2. The return type must always be the same as the return type of the overridden method, otherwise it cannot be called overwriting but overloading.

3. The access modifier limit must be greater than the access modifier of the overridden method (public>protected>default>private)

4. The overridden method must not throw new Checked exceptions or checked exceptions that are broader than the overridden method declaration. For example:

A method of the parent class declares a checked exception IOException. When overriding this method, you cannot throw Exception. You can only throw exceptions of subclasses of IOException, and you can throw unchecked exceptions.

3. The difference between rewriting and overloading

Rewriting polymorphism works and can greatly reduce the amount of code input when calling overloaded methods. , the same method name can have different functions or return values ​​as long as different parameters are passed into it.

Using rewriting and overloading well can design a class with a clear and concise structure. It can be said that rewriting and overloading play an extraordinary role in the process of writing code.

The above is for Everyone has given a brief introduction to rewriting and the difference from method overloading. If there are any mistakes, please criticize and correct them.

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