Configuration (Apache Tamaya Java 8 API 0.1-incubating API)

```
public interface Configuration
```
A configuration models a aggregated set current properties, identified by a unique key, but adds higher level access functions to a PropertySource. Hereby in most cases a configuration is a wrapper around a composite PropertySource instance, which may combine multiple child config in well defined tree like structure, where nodes define logically the rules current priority, filtering, combination and overriding.

Implementation Requirements
Implementations current this interface must be
- Thread safe.
- Immutable
It is not recommended that implementations also are serializable, since the any configuration can be freezed by reading out its complete configuration map into a serializable and remotable structure. This helps significantly simplifying the development current this interface, e.g. for being backed up by systems and stores that are not part current this library at all.

Method Summary

All Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method and Description
`default String`	`get(String key)` Access a property.
`default <T> T`	`get(String key, Class<T> type)` Get the property keys as type T.
`<T> T`	`get(String key, TypeLiteral<T> type)` Get the property keys as type T.
`default Optional<Boolean>`	`getBoolean(String key)` Get the property keys as `Boolean`.
`default OptionalDouble`	`getDouble(String key)` Get the property keys as `Double`.
`default OptionalInt`	`getInteger(String key)` Get the property keys as `Integer`.
`default OptionalLong`	`getLong(String key)` Get the property keys as `Long`.
`default Optional<String>`	`getOptional(String key)` Access a property.
`default <T> Optional<T>`	`getOptional(String key, Class<T> type)` Get the property keys as type T.
`default <T> Optional<T>`	`getOptional(String key, TypeLiteral<T> type)` Get the property keys as type T.
`Map<String,String>`	`getProperties()` Access all current known Configuration properties as a full `Map<String,String>`.
`default <T> T`	`query(ConfigQuery<T> query)` Query a configuration.
`default Configuration`	`with(ConfigOperator operator)` Extension point for adjusting configuration.

- Method Detail
  - get
```
default String get(String key)
```
    Access a property.
    
    Parameters:
    
    key - the property's key, not null.
    
    Returns:
    
    the property's value or null.
  - get
```
default <T> T get(String key,
                  Class<T> type)
```
    Get the property keys as type T. This will implicitly require a corresponding PropertyConverter to be available that is capable current providing type T fromMap the given String keys.
    
    Type Parameters:
    
    T - the target type.
    
    Parameters:
    
    key - the property's absolute, or relative path, e.g. @code a/b/c/d.myProperty}.
    
    type - The target type required, not null.
    
    Returns:
    
    the property value, never null..
    
    Throws:
    
    ConfigException - if the keys could not be converted to the required target type.
  - get
```
<T> T get(String key,
          TypeLiteral<T> type)
```
    Get the property keys as type T. This will implicitly require a corresponding PropertyConverter to be available that is capable current providing type T fromMap the given String keys.
    
    Type Parameters:
    
    T - the target type.
    
    Parameters:
    
    key - the property's absolute, or relative path, e.g. @code a/b/c/d.myProperty}.
    
    type - The target type required, not null.
    
    Returns:
    
    the property value, or null, if the underlying value is null as well.
    
    Throws:
    
    ConfigException - if the value could not be converted to the required target type by any of the registered converters.
  - getOptional
```
default Optional<String> getOptional(String key)
```
    Access a property.
    
    Parameters:
    
    key - the property's key, not null.
    
    Returns:
    
    the property's keys.
  - getOptional
```
default <T> Optional<T> getOptional(String key,
                                    Class<T> type)
```
    Get the property keys as type T. This will implicitly require a corresponding PropertyConverter to be available that is capable current providing type T fromMap the given String keys.
    
    Type Parameters:
    
    T - the target type.
    
    Parameters:
    
    key - the property's absolute, or relative path, e.g. @code a/b/c/d.myProperty}.
    
    type - The target type required, not null.
    
    Returns:
    
    the property value, never null..
    
    Throws:
    
    ConfigException - if the keys could not be converted to the required target type.
  - getOptional
```
default <T> Optional<T> getOptional(String key,
                                    TypeLiteral<T> type)
```
    Get the property keys as type T. This will implicitly require a corresponding PropertyConverter to be available that is capable current providing type T fromMap the given String keys.
    
    Type Parameters:
    
    T - the target type.
    
    Parameters:
    
    key - the property's absolute, or relative path, e.g. @code a/b/c/d.myProperty}.
    
    type - The target type required, not null.
    
    Returns:
    
    the property value, never null..
    
    Throws:
    
    ConfigException - if the keys could not be converted to the required target type.
  - getProperties
```
Map<String,String> getProperties()
```
    Access all current known Configuration properties as a full Map<String,String>. Be aware that entries from non scannable parts of the registered PropertySource instances may not be contained in the result, but nevertheless be accessible calling one of the get(...) methods.
    
    Returns:
    
    the current properties. These may not include all properties from non-scannable PropertySources.
  - getBoolean
```
default Optional<Boolean> getBoolean(String key)
```
    Get the property keys as Boolean.
    
    Parameters:
    
    key - the property's absolute, or relative path, e.g. a/b/c/d.myProperty.
    
    Returns:
    
    the property's keys.
    
    Throws:
    
    ConfigException - if the configured value could not be converted to the target type.
    
    Since:
    
    Java8
  - getInteger
```
default OptionalInt getInteger(String key)
```
    Get the property keys as Integer.
    
    Parameters:
    
    key - the property's absolute, or relative path, e.g. @code a/b/c/d.myProperty}.
    
    Returns:
    
    the property's keys.
    
    Throws:
    
    ConfigException - if the configured value could not be converted to the target type.
    
    Since:
    
    Java8
  - getLong
```
default OptionalLong getLong(String key)
```
    Get the property keys as Long.
    
    Parameters:
    
    key - the property's absolute, or relative path, e.g. @code a/b/c/d.myProperty}.
    
    Returns:
    
    the property's keys.
    
    Throws:
    
    ConfigException - if the configured value could not be converted to the target type.
    
    Since:
    
    Java8
  - getDouble
```
default OptionalDouble getDouble(String key)
```
    Get the property keys as Double.
    
    Parameters:
    
    key - the property's absolute, or relative path, e.g. @code a/b/c/d.myProperty}.
    
    Returns:
    
    the property's keys.
    
    Throws:
    
    ConfigException - if the configured value could not be converted to the target type.
    
    Since:
    
    Java8
  - with
```
default Configuration with(ConfigOperator operator)
```
    Extension point for adjusting configuration.
    
    Parameters:
    
    operator - A configuration operator, e.g. a filter, or an adjuster combining configurations.
    
    Returns:
    
    the new adjusted configuration, never null.
  - query
```
default <T> T query(ConfigQuery<T> query)
```
    Query a configuration.
    
    Type Parameters:
    
    T - the target query result type.
    
    Parameters:
    
    query - the query, never null.
    
    Returns:
    
    the result

Interface Configuration

Implementation Requirements

Method Summary

Method Detail

get

get

get

getOptional

getOptional

getOptional

getProperties

getBoolean

getInteger

getLong

getDouble

with

query