使用构建者的一种情况
- 遇到多个构造器参数时考虑使用
相关代码:
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 {
private final int servingSize;
private final int serving;
private int calories = 0;
private int fat = 0;
private int sodium = 0;
private int carbonhydrate;
public Builder(int servingSize, int serving) {
this.servingSize = servingSize;
this.serving = serving;
}
public Builder calories(int val) {
calories = val;
return this;
}
public Builder fat(int val) {
fat = val;
return this;
}
public Builder sodium(int val) {
sodium = val;
return this;
}
public Builder carbonhydrate(int val) {
carbonhydrate = val;
return this;
}
public NutritionFacts build() {
return new NutritionFacts(this);
}
}
private NutritionFacts(Builder builder) {
servingSize = builder.servingSize;
servings = builder.serving;
calories = builder.calories;
fat = builder.fat;
sodium = builder.sodium;
carbohydrate = builder.carbonhydrate;
}
}
调用方法:
NutritionFacts nutritionFacts = new NutritionFacts.Builder(230, 4).
calories(0).fat(0).sodium(0).carbonhydrate(0).build();
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