在我的构建模式中找不到匹配的构造函数错误

Question

我正在尝试使用有效的Java书并享受它。我阅读Builder模式，我试着玩它。我有这样的代码（在Groovy）：

public class Anto { 
    public static void main(String[] args) { 

      def testing = new Java.Builder(1).author("antoaravinth").build() 
      println testing.author 
     } 
} 

class Java { 
    int version 
    def author 
    int release_number 

    public static class Builder { 
     int version 

     def author = "" 
     int release_number = 0 

     public Builder(int version) { 
      this.version = version 
     } 

     public Builder version(int version) 
     { 
      version = version 
      return this 
     } 

     public Builder author(def author) 
     { 
      author = author 
      return this 
     } 

     public Builder release_number(int release_number) 
     { 
      release_number = release_number 
      return this 
     } 

     public Java build() { 
      return new Java(this); 
     } 


     private Java(Builder builder) 
     { 
      version = builder.version 
      author = builder.author 
      release_number = builder.release_number 
     } 

    } 
} 

，但我得到的错误是这样的：

Caught: groovy.lang.GroovyRuntimeException: Could not find matching constructor for: Java(Java$Builder) 
groovy.lang.GroovyRuntimeException: Could not find matching constructor for: Java(Java$Builder) 
    at Java$Builder.build(Anto.groovy:43) 
    at Java$Builder$build.call(Unknown Source) 
    at Anto.main(Anto.groovy:4) 

我不知道为什么会这样！我哪里出错了？

Answer 1

这是您的build()方法：

public Java build() { 
    return new Java(this); 
} 

看看你Java类（不是Builder） - 它没有任何明确的声明构造，因此它具有唯一的构造是公参一个为您自动宣布。

您需要将这样的：

private Java(Builder builder) 
{ 
    version = builder.version 
    author = builder.author 
    release_number = builder.release_number 
} 

的Builder类之外。 （我有点惊讶的Groovy没有抱怨，但我敢肯定，这是问题...）

编辑：现在它不是抛出一个异常，看看你的“二传手”方法：

public Builder version(int version) 
{ 
    version = version 
    return this 
} 

version = version行不做任何事情。您需要区分参数和字段，例如

public Builder version(int version) 
{ 
    this.version = version 
    return this 
} 

...或者通过给参数赋予不同的名称，例如，

public Builder version(int value) 
{ 
    version = value 
    return this 
}