Groovy中的“属性”是什么？ [英] What are 'properties' in Groovy?

问题描述

groovy中的属性看起来像java中没有访问修饰符的类字段。真的吗？或者他们有特殊的含义。似乎没有办法让这些属性变成私人的？

解决方案

当一个Groovy类定义声明一个没有访问修饰符的字段时，公共setter / getter方法对和一个私有实例根据 JavaBeans规范生成的变量字段也被称为属性 >。

  class A {
字符串属性
 
 / * 
 private String属性
 
 public void setProperty（String property）{...} 
 public String getProperty（）{...} 
 * / 
} 
  

如果我们声明一个公共实例变量字段，我们只需要一个公共字段，而不需要setter / getter方法对。

  class A {
 public String field 
 
 / * 
 public String field 
 
 
 
 
 $ b 
从Groovy客户端的pov， Groovy属性和运行时的公共字段
  def a = new A（）
 println a.field 
 println a.property 
  
虽然 a.field 直接访问实例变量，并且 a.property 实际调用 a.getProperty（）（或 a.setProperty（...） wh分配一个值）。但是，由于该属性符合JavaBeans规范，因此该类可以无缝地用于基于Java的环境中。
 
 
 
我没有看到制作私有属性 。  private 限制方法或实例/类变量对托管类类型的使用。但也许你是指制作私人字段实例变量。
 
Properties in groovy seem like class fields in java without an access modifier. Is that true? Or they have a special meaning. It seems like there is no way to make the properties private? 
解决方案
When a Groovy class definition declares a field  without an access modifier, then a public setter/getter method pair and a private instance variable field is generated which is also known as "property" according to the JavaBeans specification. 
class A {
    String property

    /* 
         private String property

         public void setProperty(String property) { ... }
         public String getProperty() { ... }
    */
}
If we declare a public instance variable field we just get a public field, without a setter/getter method pair.
class A {
    public String field

    /* 
         public String field
    */
}
From a Groovy client's pov, there is no difference between accessing a Groovy property and  a public field at runtime
def a = new A()
println a.field
println a.property
although a.field accesses the instance variable directly and a.property actually calls a.getProperty() (or a.setProperty(...) when assigning a value). But as the property complies to the JavaBeans spec, the class can seamlessly be used in Java-based environments.

I do not see much sense in making a "private property". private restricts the use of a method or instance/class variable to the hosting class type. But maybe you were referring to making a private field instance variable.

                        
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