How to use a nested Java Builder Class to construct an object?

Riley Gibbs

2015 6 29

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5 次查看（30 天）

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I'm currently trying to import and use a class that uses the Java Builder pattern and I can't seem to figure out how to instantiate an instance of the object. Below is my class setup and how I'd build it in Java for reference.

package testJavaBuilder;
public class NutritionalFacts {
  private int sodium;
  private int fat;
  private int carbo;
    public static class Builder {
        private int sodium;
        private int fat;
        private int carbo;
        public Builder(int s) {
            this.sodium = s;
        }
        public Builder fat(int f) {
            this.fat = f;
            return this;
        }
        public Builder carbo(int c) {
            this.carbo = c;
            return this;
        }
        public NutritionalFacts build() {
            return new NutritionalFacts(this);
        }
    }
    private NutritionalFacts(Builder b) {
        this.sodium = b.sodium;
        this.fat = b.fat;
        this.carbo = b.carbo;
    }
}
NutritionalFacts facts = new NutritionalFacts.Builder(10).carbo(23).fat(1).build();

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Andrew Janke 2017-7-28

See https://www.mathworks.com/matlabcentral/answers/98620-how-do-i-create-an-instance-of-a-java-public-static-nested-class-from-inside-matlab-7-13-r2011b. You have to work around this by using Java Reflection calls or writing a custom Java adapter class.

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