Package com.typesafe.config

Interface ConfigValue

  • All Superinterfaces:
    ConfigMergeable
    All Known Subinterfaces:
    ConfigList, ConfigObject
    public interface ConfigValue
extends ConfigMergeable
    An immutable value, following the JSON type schema.

    Because this object is immutable, it is safe to use from multiple threads and there's no need for "defensive copies."

    Do not implement interface ConfigValue; it should only be implemented by the config library. Arbitrary implementations will not work because the library internals assume a specific concrete implementation. Also, this interface is likely to grow new methods over time, so third-party implementations will break.

    • Method Detail

      • origin

        origin()
        The origin of the value (file, line number, etc.), for debugging and error messages.
        Returns:
        where the value came from

      • unwrapped

        java.lang.Object unwrapped()
        Returns the value as a plain Java boxed value, that is, a String, Number, Boolean, Map<String,Object>, List<Object>, or null, matching the valueType() of this ConfigValue. If the value is a ConfigObject or ConfigList, it is recursively unwrapped.
        Returns:
        a plain Java value corresponding to this ConfigValue

      • render

        java.lang.String render()
        Renders the config value as a HOCON string. This method is primarily intended for debugging, so it tries to add helpful comments and whitespace.

        If the config value has not been resolved (see Config.resolve()), it's possible that it can't be rendered as valid HOCON. In that case the rendering should still be useful for debugging but you might not be able to parse it. If the value has been resolved, it will always be parseable.

        This method is equivalent to render(ConfigRenderOptions.defaults()).

        Returns:
        the rendered value

      • render

        java.lang.String render​(ConfigRenderOptions options)
        Renders the config value to a string, using the provided options.

        If the config value has not been resolved (see Config.resolve()), it's possible that it can't be rendered as valid HOCON. In that case the rendering should still be useful for debugging but you might not be able to parse it. If the value has been resolved, it will always be parseable.

        If the config value has been resolved and the options disable all HOCON-specific features (such as comments), the rendering will be valid JSON. If you enable HOCON-only features such as comments, the rendering will not be valid JSON.

        Parameters:
        options - the rendering options
        Returns:
        the rendered value

      • withFallback

        withFallback​(ConfigMergeable other)
        Description copied from interface: ConfigMergeable
        Returns a new value computed by merging this value with another, with keys in this value "winning" over the other one.

        This associative operation may be used to combine configurations from multiple sources (such as multiple configuration files).

        The semantics of merging are described in the spec for HOCON. Merging typically occurs when either the same object is created twice in the same file, or two config files are both loaded. For example: 

          foo = { a: 42 }
  foo = { b: 43 }
        Here, the two objects are merged as if you had written: 
          foo = { a: 42, b: 43 }

        Only ConfigObject and Config instances do anything in this method (they need to merge the fallback keys into themselves). All other values just return the original value, since they automatically override any fallback. This means that objects do not merge "across" non-objects; if you write object.withFallback(nonObject).withFallback(otherObject), then otherObject will simply be ignored. This is an intentional part of how merging works, because non-objects such as strings and integers replace (rather than merging with) any prior value: 

         foo = { a: 42 }
 foo = 10
        Here, the number 10 "wins" and the value of foo would be simply 10. Again, for details see the spec.
        Specified by:
        withFallback in interface ConfigMergeable
        Parameters:
        other - an object whose keys should be used as fallbacks, if the keys are not present in this one
        Returns:
        a new object (or the original one, if the fallback doesn't get used)

      • atPath

        atPath​(java.lang.String path)
        Places the value inside a Config at the given path. See also atKey(String).
        Parameters:
        path - path to store this value at.
        Returns:
        a Config instance containing this value at the given path.

      • atKey

        atKey​(java.lang.String key)
        Places the value inside a Config at the given key. See also atPath(String).
        Parameters:
        key - key to store this value at.
        Returns:
        a Config instance containing this value at the given key.

      • withOrigin

        withOrigin​(ConfigOrigin origin)
        Returns a ConfigValue based on this one, but with the given origin. This is useful when you are parsing a new format of file or setting comments for a single ConfigValue.
        Parameters:
        origin - the origin set on the returned value
        Returns:
        the new ConfigValue with the given origin
        Since:
        1.3.0