Constructor method Invocation of "Java Foundation" constructor

Start with a program:

1 classDog2 {3     PrivateString name;4     PrivateString color;5     Private intAge ;6 7 Dog (String name)8     //assign a value to name only9     {Ten          This. name=name; One     } A Dog (String name,string color) -     //assign a value to Name,color only -     { the          This. name=name;//But there was a similar code before. -          This. color=color; -     } -Dog (String name,string color,intAge ) +     //assign a value to Name,color,age only -     { +          This. name=name; A          This. Color=color;//There have been similar codes before at          This. age=Age ; -     } - /*The above code drawbacks, code duplication, - and if you modify the original defined parameters (such as name), - requires extensive modification of the parameters in the method (3 modifications), causing inconvenience*/ - } in  - classConstructerdemo to { +      Public Static voidMain (string[] args) -     { the  *     } $}

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In this case, we can use the constructor method to invoke the constructor method (in the form of this (argument)) to resolve the above problem, and improve as follows:

1 classDog2 {3     PrivateString name;4     PrivateString color;5     Private intAge ;6 7 Dog (String name)8     //assign a value to name only9     {Ten          This. name=name; One     } A Dog (String name,string color) -     //assign a value to Name,color only -     { the         //This.name=name;//But there was a similar code before. -          This(name);//after improvement -          This. color=color; -     } +Dog (String name,string color,intAge ) -     //assign a value to Name,color,age only +     { A         //This.name=name; at         //This.color=color;//There have been similar codes before -          This(Name,color);//after improvement -          This. age=Age ; -     } - /*The above code drawbacks, code duplication, - and if you modify the original defined parameters (such as name), in requires extensive modification of the parameters in the method (3 modifications), causing inconvenience*/ - } to  + classConstructerdemo - { the      Public Static voidMain (string[] args) *     { $ Panax Notoginseng     } -}

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We should note that the call to the this constructor must be the first statement in the constructor .

That's two. Note that the This constructor must be placed in the constructor. The second is the first statement that must be a constructor.

Java Foundation Constructor method call construction method