Package com.typesafe.config

Interface ConfigObject

All Superinterfaces:
ConfigMergeable, ConfigValue, Map<String,ConfigValue>
public interface ConfigObject extends ConfigValue, Map<String,ConfigValue>
Subtype of ConfigValue representing an object (AKA dictionary or map) value, as in JSON's curly brace { "a" : 42 } syntax.

An object may also be viewed as a Config by calling toConfig().

ConfigObject implements java.util.Map<String, ConfigValue> so you can use it like a regular Java map. Or call unwrapped() to unwrap the map to a map with plain Java values rather than ConfigValue.

Like all ConfigValue subtypes, ConfigObject is immutable. This makes it threadsafe and you never have to create "defensive copies." The mutator methods from Map all throw UnsupportedOperationException.

The ConfigValue.valueType() method on an object returns ConfigValueType.OBJECT.

In most cases you want to use the Config interface rather than this one. Call toConfig() to convert a ConfigObject to a Config.

The API for a ConfigObject is in terms of keys, while the API for a Config is in terms of path expressions. Conceptually, ConfigObject is a tree of maps from keys to values, while a Config is a one-level map from paths to values.

Use ConfigUtil.joinPath(java.lang.String...) and ConfigUtil.splitPath(java.lang.String) to convert between path expressions and individual path elements (keys).

A ConfigObject may contain null values, which will have ConfigValue.valueType() equal to ConfigValueType.NULL. If get(Object) returns Java's null then the key was not present in the parsed file (or wherever this value tree came from). If get("key") returns a ConfigValue with type ConfigValueType#NULL then the key was set to null explicitly in the config file.

Do not implement interface ConfigObject; 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 Details

    • toConfig

      Config toConfig()
      Converts this object to a Config instance, enabling you to use path expressions to find values in the object. This is a constant-time operation (it is not proportional to the size of the object).
      Returns:
      a Config with this object as its root

    • unwrapped

      Map<String,Object> unwrapped()
      Recursively unwraps the object, returning a map from String to whatever plain Java values are unwrapped from the object's values.
      Specified by:
      unwrapped in interface ConfigValue
      Returns:
      a Map containing plain Java objects

    • withFallback

      ConfigObject 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
      Specified by:
      withFallback in interface ConfigValue
      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)

    • get

      ConfigValue get(Object key)
      Gets a ConfigValue at the given key, or returns null if there is no value. The returned ConfigValue may have ConfigValueType.NULL or any other type, and the passed-in key must be a key in this object (rather than a path expression).
      Specified by:
      get in interface Map<String,ConfigValue>
      Parameters:
      key - key to look up
      Returns:
      the value at the key or null if none

    • withOnlyKey

      ConfigObject withOnlyKey(String key)
      Clone the object with only the given key (and its children) retained; all sibling keys are removed.
      Parameters:
      key - key to keep
      Returns:
      a copy of the object minus all keys except the one specified

    • withoutKey

      ConfigObject withoutKey(String key)
      Clone the object with the given key removed.
      Parameters:
      key - key to remove
      Returns:
      a copy of the object minus the specified key

    • withValue

      ConfigObject withValue(String key, ConfigValue value)
      Returns a ConfigObject based on this one, but with the given key set to the given value. Does not modify this instance (since it's immutable). If the key already has a value, that value is replaced. To remove a value, use withoutKey(String).
      Parameters:
      key - key to add
      value - value at the new key
      Returns:
      the new instance with the new map entry

    • withOrigin

      ConfigObject withOrigin(ConfigOrigin origin)
      Description copied from interface: ConfigValue
      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.
      Specified by:
      withOrigin in interface ConfigValue
      Parameters:
      origin - the origin set on the returned value
      Returns:
      the new ConfigValue with the given origin