Effective Java Item2:consider A builder when faced with many constructor parameters

Item2:consider a builder when faced with many constructor parameters

When a constructor method has more than one parameter, you can consider using the builder approach for processing.

Instance code:

 Public classnutritionfacts {Private Final intservingsize; Private Final intservings; Private Final intcalories; Private Final intfat; Private Final intsodium; Private Final intcarbohydrate;  Public Static classbuilder{//The following two parameters are required        Private Final intservingsize; Private Final intservings; Private intCalories = 0; Private intFat = 0; Private intSodium = 0; Private intcarbohydrate= 0;  PublicBuilder (intServingsize,intservings) {             This. servingsize =servingsize;  This. servings =servings; }                 PublicBuilder Calories (intval) {Calories=Val; return  This; }                 PublicBuilder Fat (intval) {Fat=Val; return  This; }                 PublicBuilder Sodium (intval) {Sodium=Val; return  This; }                 PublicBuilder Carbohydrate (intval) {Carbohydrate=Val; return  This; }                 Publicnutritionfacts Build () {return NewNutritionfacts ( This); }    }        Privatenutritionfacts (Builder builder) {Servingsize=builder.servingsize; Servings=builder.servings; Calories=builder.calories; Fat=Builder.fat; Sodium=Builder.sodium; Carbohydrate=builder.carbohydrate; }}

How to use:

 Public class Test {    publicstaticvoid  main (string[] args) {        new nutritionfacts.builder (                calories). Sodium (+). Carbohydrate (). build ();}    

Effective Java Item2:consider a builder when faced with many constructor parameters