在我的構建模式中找不到匹配的構造函數錯誤

Question

我正在嘗試使用有效的Java書並享受它。我閱讀Builder模式，我試着玩它。我有這樣的代碼（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 
     } 

    } 
} 

，但我得到的錯誤是這樣的：

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) 

我不知道爲什麼會這樣！我哪裏出錯了？

Answer 1

這是您的build()方法：

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

看看你Java類（不是Builder） - 它沒有任何明確的聲明構造，因此它具有唯一的構造是公參一個爲您自動宣佈。

您需要將這樣的：

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

的Builder類之外。 （我有點驚訝的Groovy沒有抱怨，但我敢肯定，這是問題...）

編輯：現在它不是拋出一個異常，看看你的「二傳手」方法：

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

version = version行不做任何事情。您需要區分參數和字段，例如

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

...或者通過給參數賦予不同的名稱，例如，

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