Summary of considerations for Java construction methods

Construction Method Details Summary ~~~~~

1: First to understand why you need to construct a method ,, there are too many properties in the class, each time to assign a value to the property is very troublesome: the encoding is large, you cannot reuse the code to assign value to the property.

2: What is a construction method?

The constructor method is responsible for initializing the instance variables in the class.
The constructor method is a special method that must satisfy the following syntax rules:

A: The construction method must be the same as the class name, and does not contain a return value type Description section.
B: The construction method cannot have static and final keyword adornments.

3: How do I use the construction method? call construction method using the New keyword

4: Display construction method and implicit construction method

　　When you create a class, if you do not explicitly define a construction method, there is a default parameterless construction method for that class;
You can declare one or more arguments in a class, but each construction method has a difference in the number of arguments or parameter data Types!!!

!!!!!!!!!!

　　If an explicit construction method exists in a class, the default parameterless construction method will no longer exist unless you explicitly define an parameterless construction method

There can be more than one constructor in a class, the constructor can be called through this implementation, but the calling constructor code must be written in the first line of the valid code, which is very important oh ~

1  Packageconstructor;2 3  Public classApple {4 5     PrivateString name;6     PrivateString color;7     Private DoublePrice ;8     9     //Non-parametric construction methodTen      PublicApple () { One          A     } -  -      PublicApple (String name) { the          This. Name =name; -     } -      -     //multiple constructor methods, which are identical to the type of the parameter and the type of the parameter in the constructor method when called +      PublicApple (string name, string color,DoublePrice ) { -          This(name);//the call in the constructor method is called with this (parameter), but note that a call to another constructor method can only be made once in a constructor method.  +          This. color =color; A          This. Price =Price ; at     } -      -      Public Static voidMain (string[] args) { -Apple apple1=NewApple ("Apple"); -Apple apple2=NewApple ("Apple", "Red", 12.5); -     } in      -      to}

Summary of considerations for Java construction methods