稍后如何在这里初始化final？ [复制]

Question

所以在看书的时候，我发现了这段代码。

public class NutritionFacts {
private final int servingSize; // (mL) required
private final int servings; // (per container) required
private final int calories; // (per serving) optional
private final int fat; // (g/serving) optional
private final int sodium; // (mg/serving) optional
private final int carbohydrate; // (g/serving) optional
public NutritionFacts(int servingSize, int servings) {
this(servingSize, servings, 0);
}

public NutritionFacts(int servingSize, int servings,
int calories) {
this(servingSize, servings, calories, 0);
}

public NutritionFacts(int servingSize, int servings,
int calories, int fat) {
this(servingSize, servings, calories, fat, 0);
}

public NutritionFacts(int servingSize, int servings,
int calories, int fat, int sodium) {
this(servingSize, servings, calories, fat, sodium, 0);
public NutritionFacts(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;
}
}

所以在这里，final 关键字用在营养名称之前。但它们也在代码的后面部分进行了初始化。那可能吗？因为一旦一个变量被标记为final，以后就不能再初始化了。

Answer 1

final 关键字意味着一个属性的值只能设置一次。这就是这种情况，因为您只在构造函数中设置了值。所以这是有效的代码。