多种方法,我发现调用Java的多种方法中的一种新的方式,我真的不明白发生了什么事背后:调用Java中
public class NutritionFacts {
private final int servingSize;
private final int servings;
private final int calories;
private final int fat;
private final int sodium;
private final int carbohydrate;
public static class Builder {
// Required parameters
private final int servingSize;
private final int servings;
// Optional parameters - initialized to default values
private int calories = 0;
private int fat = 0;
private int carbohydrate = 0;
private int sodium = 0;
public Builder(int servingSize, int servings) {
this.servingSize = servingSize;
this.servings = servings;
}
public Builder calories(int val)
{ calories = val; return this; }
public Builder fat(int val)
{ fat = val; return this; }
public Builder carbohydrate(int val)
{ carbohydrate = val; return this; }
public Builder sodium(int val)
{ sodium = val; return this; }
public NutritionFacts build() {
return new NutritionFacts(this);
}
}
private NutritionFacts(Builder builder) {
servingSize = builder.servingSize;
servings = builder.servings;
calories = builder.calories;
}
}
现在的类实例化使用这一行,这里就是它得到混淆:
NutritionFacts cocaCola = new NutritionFacts.Builder(240, 8).calories(100).sodium(35).carbohydrate(27).build();
这一切都有道理,直到NutritionFacts.Build(int,int),在那之后,究竟发生了什么?为什么Builder类中的calories
,sodium
,carbohydrate
方法需要返回this
?那个班级的地址在哪里?
谢谢!
这是否意味着从foo.calories返回值(12),这是实例,用于调用线下一种方法,在我们的例子中,钠(35)? –
@ Cookie503绝对:) –
@ Cookie503没错。 –