The difference between "rewrite" and "overload"

Method rewriting

• Override Method rewriting ： In the inheritance relationship , If a subclass defines a method with exactly the same method name and parameters as the parent class , We call it rewriting （Override）, That is , The subclass has the same method declaration as the parent class .
• Application of method rewriting ： When a child class needs the function of a parent class , When the subclass of function subject has its own unique content , You can override methods in the parent class , such , It follows the function of the parent class , It also defines the specific content of the subclass .
• @Override

        ① It's an annotation

        ② It can help us check the correctness of the rewrite method declaration

Method rewrite considerations ：

        ① Private methods cannot be overridden （ Private members of a parent class cannot be inherited from a child class ）

        ② Subclass method access rights cannot A lower （ private < Default <public）

What is overload ？

Overload Method overloading ：

• Multiple methods in the same class
• Multiple methods have the same method name
• Multiple method parameters are different , Different in type or quantity

Method overload features ： 

• Overloads only correspond to the definition of methods , It has nothing to do with the method call , The call mode refers to the standard format
• Overloads only identify the names and parameters of methods in the same class , Independent of the return value , That is, you cannot determine whether the two methods constitute overloads by the return value

Code block 1： Does not constitute a heavy load  

public class Demo01{
    public static void dosth(int a){
        // Method body 
    }
    public static int dosth(int a){
        // Method body 
    }
}

Code block 2： Constitute heavy load

public class Demo02{
    public static void dosth(int a){
        // Method body 
    }
    public static int dosth(int a,int b){
        // Method body 
    }
}

The purpose of method overloading ： Use the same method name for methods with similar functions , Easy to remember , It is also simpler to call

  Be careful ： The return value types of method overloads are usually the same

summary ：

        in general , If the method name and parameters of the method are different , That's it （Overload） heavy load ,（Overload） heavy load The method of is a new method ; If the method name and parameters are the same , And the return value is the same , That's it （Override） rewrite .