标签：pac cti color get 不一致 新特性 卡路里 val ret
创建Java对象时，对于可为空的属性，创建对象的时候有3种模式：重叠构造器模式、JavaBeans模式、Builder模式（推荐）、Stream模式（推荐）。
package effectiveJava.builder;
public class NutritionFactsMultiContr {
//食物尺寸
private int servingSize;
//食物数量
private int servings;
//热量（卡路里）
private int calories;
//脂肪含量
private int fat;
//食用盐（钠）含量
private int sodium;
//糖类含量
private int carbohydrate;
public NutritionFactsMultiContr(int servingSize, int servings) {
this(servingSize,servings,0);
}
public NutritionFactsMultiContr(int servingSize, int servings, int calories) {
this(servingSize,servings,calories,0);
}
public NutritionFactsMultiContr(int servingSize, int servings, int calories, int fat) {
this(servingSize,servings,calories,fat,0);
}
public NutritionFactsMultiContr(int servingSize, int servings, int calories, int fat, int sodium) {
this(servingSize,servings,calories,fat,sodium,0);
}
public NutritionFactsMultiContr(int servingSize, int servings, int calories, int fat, int sodium, int carbohydrate) {
this.servingSize = servingSize;
this.servings = servings;
this.calories = calories;
this.fat = fat;
this.sodium = sodium;
this.carbohydrate = carbohydrate;
}
public static void main(String[] args) {
NutritionFactsMultiContr nutritionFacts = new NutritionFactsMultiContr(1,2,3,4,5,6);
}
}
package effectiveJava.builder;
//营养成分
public class NutritionFactsSetter {
//食物尺寸
private int servingSize;
//食物数量
private int servings;
//热量（卡路里）
private int calories;
//脂肪含量
private int fat;
//食用盐（钠）含量
private int sodium;
//糖类含量
private int carbohydrate;
public void setServingSize(int servingSize) {
this.servingSize = servingSize;
}
public void setServings(int servings) {
this.servings = servings;
}
public void setCalories(int calories) {
this.calories = calories;
}
public void setFat(int fat) {
this.fat = fat;
}
public void setSodium(int sodium) {
this.sodium = sodium;
}
public void setCarbohydrate(int carbohydrate) {
this.carbohydrate = carbohydrate;
}
public static void main(String[] args) {
NutritionFactsSetter nutritionFacts = new NutritionFactsSetter();
nutritionFacts.setCalories(1);
nutritionFacts.setCarbohydrate(2);
}
}
package effectiveJava.builder;
//营养成分
public class NutritionFacts {
//食物尺寸
private int servingSize;
//食物数量
private int servings;
//热量（卡路里）
private int calories;
//脂肪含量
private int fat;
//食用盐（钠）含量
private int sodium;
//糖类含量
private int carbohydrate;
/**
* NutritionFacts是不可变的，不对外提供构造器
* @param builder
*/
private NutritionFacts(Builder builder) {
this.servingSize = builder.servingSize;
this.servings = builder.servings;
this.calories = builder.calories;
this.fat = builder.fat;
this.sodium = builder.sodium;
this.carbohydrate = builder.carbohydrate;
}
public static class Builder {
private int servingSize;
private int servings;
private int calories;
private int fat;
private int sodium;
private int carbohydrate;
//必填字段
public Builder(int servingSize, int servings) {
this.servingSize = servingSize;
this.servings = servings;
}
//可选字段
public Builder calories(int val){
this.calories = val;
return this;
}
public Builder fat(int val){
this.fat = val;
return this;
}
public Builder sodium(int val){
this.sodium = val;
return this;
}
public Builder carbohydrate(int val){
this.carbohydrate = val;
return this;
}
public NutritionFacts build() {
return new NutritionFacts(this);
}
}
public static void main(String[] args) {
NutritionFacts facts = new NutritionFacts.Builder(1, 2).calories(3).fat(4).build();
}
}
package effectiveJava.builder;
public class NutritionFactsStream {
//食物尺寸
private int servingSize;
//食物数量
private int servings;
//热量（卡路里）
private int calories;
//脂肪含量
private int fat;
//食用盐（钠）含量
private int sodium;
//糖类含量
private int carbohydrate;
public NutritionFactsStream() {
}
public int getServingSize() {
return servingSize;
}
public NutritionFactsStream setServingSize(int servingSize) {
this.servingSize = servingSize;
return this;
}
public int getServings() {
return servings;
}
public NutritionFactsStream setServings(int servings) {
this.servings = servings;
return this;
}
public int getCalories() {
return calories;
}
public NutritionFactsStream setCalories(int calories) {
this.calories = calories;
return this;
}
public int getFat() {
return fat;
}
public NutritionFactsStream setFat(int fat) {
this.fat = fat;
return this;
}
public int getSodium() {
return sodium;
}
public NutritionFactsStream setSodium(int sodium) {
this.sodium = sodium;
return this;
}
public int getCarbohydrate() {
return carbohydrate;
}
public NutritionFactsStream setCarbohydrate(int carbohydrate) {
this.carbohydrate = carbohydrate;
return this;
}
public static void main(String[] args) {
NutritionFactsStream nutritionFacts = new NutritionFactsStream().setServings(1).setServings(2);
}
}
此外，创建对象的模式还有很多，比如：工厂模式、单例模式等，不是本文讨论的重点，有兴趣的可以自己研究一下。
参考资料：
标签：pac cti color get 不一致 新特性 卡路里 val ret
原文地址：https://www.cnblogs.com/BlueStarWei/p/13335632.html
