Package org.apache.commons.configuration2

Interface ImmutableConfiguration

All Known Subinterfaces:
Configuration, FileBasedConfiguration, HierarchicalConfiguration<T>, ImmutableHierarchicalConfiguration
All Known Implementing Classes:
AbstractConfiguration, AbstractHierarchicalConfiguration, AbstractYAMLBasedConfiguration, AppletConfiguration, BaseConfiguration, BaseHierarchicalConfiguration, CombinedConfiguration, CompositeConfiguration, DatabaseConfiguration, DataConfiguration, DynamicCombinedConfiguration, EnvironmentConfiguration, INIConfiguration, JNDIConfiguration, JSONConfiguration, MapConfiguration, PatternSubtreeConfigurationWrapper, PropertiesConfiguration, PropertyListConfiguration, ServletConfiguration, ServletContextConfiguration, ServletFilterConfiguration, ServletRequestConfiguration, SubnodeConfiguration, SubsetConfiguration, SystemConfiguration, XMLConfiguration, XMLPropertiesConfiguration, XMLPropertyListConfiguration, YAMLConfiguration
public interface ImmutableConfiguration

The main interface for accessing configuration data in a read-only fashion.

The major part of the methods defined in this interface deals with accessing properties of various data types. There is a generic getProperty() method, which returns the value of the queried property in its raw data type. Other getter methods try to convert this raw data type into a specific data type. If this fails, a ConversionException will be thrown.

For most of the property getter methods an overloaded version exists that allows to specify a default value, which will be returned if the queried property cannot be found in the configuration. The behavior of the methods that do not take a default value in case of a missing property is not defined by this interface and depends on a concrete implementation. E.g. the AbstractConfiguration class, which is the base class of most configuration implementations provided by this package, per default returns null if a property is not found, but provides the setThrowExceptionOnMissing() method, with which it can be configured to throw a NoSuchElementException exception in that case. (Note that getter methods for primitive types in AbstractConfiguration always throw an exception for missing properties because there is no way of overloading the return value.)

Since:
2.0

  • Method Details

    • containsKey

      boolean containsKey(String key)
      Checks if the configuration contains the specified key.
      Parameters:
      key - the key whose presence in this configuration is to be tested
      Returns:
      true if the configuration contains a value for this key, false otherwise

    • get

      <T> T get(Class<T> cls, String key)
      Gets an object of the specified type associated with the given configuration key. If the key doesn't map to an existing object, the method returns null unless AbstractConfiguration.isThrowExceptionOnMissing() is set to true.
      Type Parameters:
      T - the target type of the value
      Parameters:
      cls - the target class of the value
      key - the key of the value
      Returns:
      the value of the requested type for the key
      Throws:
      NoSuchElementException - if the key doesn't map to an existing object and throwExceptionOnMissing=true
      ConversionException - if the value is not compatible with the requested type
      Since:
      2.0

    • get

      <T> T get(Class<T> cls, String key, T defaultValue)
      Gets an object of the specified type associated with the given configuration key using a default value. If the key doesn't map to an existing object, the default value is returned.
      Type Parameters:
      T - the target type of the value
      Parameters:
      cls - the target class of the value
      key - the key of the value
      defaultValue - the default value
      Returns:
      the value of the requested type for the key
      Throws:
      ConversionException - if the value is not compatible with the requested type
      Since:
      2.0

    • getArray

      Object getArray(Class<?> cls, String key)
      Gets an array of typed objects associated with the given configuration key. If the key doesn't map to an existing object, an empty list is returned.
      Parameters:
      cls - the type expected for the elements of the array
      key - The configuration key.
      Returns:
      The associated array if the key is found, and the value compatible with the type specified.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not compatible with a list of the specified class.
      Since:
      2.0

    • getArray

      @Deprecated Object getArray(Class<?> cls, String key, Object defaultValue)
      Deprecated.
      This method should not be used any more because its signature does not allow type-safe invocations; use get(Class, String, Object) instead which offers the same functionality; for instance, to query for an array of ints use int[] result = config.get(int[].class, "myArrayKey", someDefault);.
      Gets an array of typed objects associated with the given configuration key. If the key doesn't map to an existing object, the default value is returned.
      Parameters:
      cls - the type expected for the elements of the array
      key - the configuration key.
      defaultValue - the default value
      Returns:
      The associated array if the key is found, and the value compatible with the type specified.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not compatible with an array of the specified class.
      IllegalArgumentException - if the default value is not an array of the specified type
      Since:
      2.0

    • getBigDecimal

      BigDecimal getBigDecimal(String key)
      Gets a BigDecimal associated with the given configuration key.
      Parameters:
      key - The configuration key.
      Returns:
      The associated BigDecimal if key is found and has valid format

    • getBigDecimal

      BigDecimal getBigDecimal(String key, BigDecimal defaultValue)
      Gets a BigDecimal associated with the given configuration key. If the key doesn't map to an existing object, the default value is returned.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated BigDecimal if key is found and has valid format, default value otherwise.

    • getBigInteger

      BigInteger getBigInteger(String key)
      Gets a BigInteger associated with the given configuration key.
      Parameters:
      key - The configuration key.
      Returns:
      The associated BigInteger if key is found and has valid format

    • getBigInteger

      BigInteger getBigInteger(String key, BigInteger defaultValue)
      Gets a BigInteger associated with the given configuration key. If the key doesn't map to an existing object, the default value is returned.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated BigInteger if key is found and has valid format, default value otherwise.

    • getBoolean

      boolean getBoolean(String key)
      Gets a boolean associated with the given configuration key.
      Parameters:
      key - The configuration key.
      Returns:
      The associated boolean.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Boolean.

    • getBoolean

      boolean getBoolean(String key, boolean defaultValue)
      Gets a boolean associated with the given configuration key. If the key doesn't map to an existing object, the default value is returned.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated boolean.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Boolean.

    • getBoolean

      Boolean getBoolean(String key, Boolean defaultValue)
      Gets a Boolean associated with the given configuration key.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated boolean if key is found and has valid format, default value otherwise.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Boolean.

    • getByte

      byte getByte(String key)
      Gets a byte associated with the given configuration key.
      Parameters:
      key - The configuration key.
      Returns:
      The associated byte.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Byte.

    • getByte

      byte getByte(String key, byte defaultValue)
      Gets a byte associated with the given configuration key. If the key doesn't map to an existing object, the default value is returned.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated byte.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Byte.

    • getByte

      Byte getByte(String key, Byte defaultValue)
      Gets a Byte associated with the given configuration key.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated byte if key is found and has valid format, default value otherwise.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Byte.

    • getCollection

      <T> Collection<T> getCollection(Class<T> cls, String key, Collection<T> target)
      Gets a collection of typed objects associated with the given configuration key. This method works like getCollection(Class, String, Collection, Collection) passing in null as default value.
      Type Parameters:
      T - the element type of the result list
      Parameters:
      cls - the element class of the result list
      key - the configuration key
      target - the target collection (may be null)
      Returns:
      the collection to which data was added
      Throws:
      ConversionException - if the conversion is not possible
      Since:
      2.0

    • getCollection

      <T> Collection<T> getCollection(Class<T> cls, String key, Collection<T> target, Collection<T> defaultValue)
      Gets a collection of typed objects associated with the given configuration key using the values in the specified default collection if the key does not map to an existing object. This method is similar to getList(), however, it allows specifying a target collection. Results are added to this collection. This is useful if the data retrieved should be added to a specific kind of collection, e.g. a set to remove duplicates. The return value is as follows:
      • If the key does not map to an existing object and the default value is null, the method returns null.
      • If the target collection is not null and data has been added (either from the resolved property value or from the default collection), the target collection is returned.
      • If the target collection is null and data has been added (either from the resolved property value or from the default collection), return value is the target collection created by this method.
      Type Parameters:
      T - the element type of the result list
      Parameters:
      cls - the element class of the result list
      key - the configuration key
      target - the target collection (may be null)
      defaultValue - the default value (may be null)
      Returns:
      the collection to which data was added
      Throws:
      ConversionException - if the conversion is not possible
      Since:
      2.0

    • getDouble

      double getDouble(String key)
      Gets a double associated with the given configuration key.
      Parameters:
      key - The configuration key.
      Returns:
      The associated double.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Double.

    • getDouble

      double getDouble(String key, double defaultValue)
      Gets a double associated with the given configuration key. If the key doesn't map to an existing object, the default value is returned.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated double.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Double.

    • getDouble

      Double getDouble(String key, Double defaultValue)
      Gets a Double associated with the given configuration key.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated double if key is found and has valid format, default value otherwise.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Double.

    • getDuration

      default Duration getDuration(String key)
      Gets a Duration associated with the given configuration key.
      Parameters:
      key - The configuration key.
      Returns:
      The associated Duration if key is found and has valid format, default value otherwise.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Duration.
      Since:
      2.8.0

    • getDuration

      default Duration getDuration(String key, Duration defaultValue)
      Gets a Duration associated with the given configuration key.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated Duration if key is found and has valid format, default value otherwise.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Duration.
      Since:
      2.8.0

    • getEncodedString

      String getEncodedString(String key)
      Gets the value of a string property that is stored in encoded form in this configuration using a default ConfigurationDecoder. This method works like the method with the same name, but it uses a default ConfigurationDecoder associated with this configuration. It depends on a specific implementation how this default decoder is obtained.
      Parameters:
      key - the configuration key
      Returns:
      the plain string value of the specified encoded property

    • getEncodedString

      String getEncodedString(String key, ConfigurationDecoder decoder)
      Gets the value of a string property that is stored in encoded form in this configuration. This method obtains the value of the string property identified by the given key. This value is then passed to the provided ConfigurationDecoder. The value returned by the ConfigurationDecoder is passed to the caller. If the key is not associated with a value, the decoder is not invoked; depending on this configuration's settings either null is returned or an exception is thrown.
      Parameters:
      key - the configuration key
      decoder - the ConfigurationDecoder (must not be null)
      Returns:
      the plain string value of the specified encoded property
      Throws:
      IllegalArgumentException - if a null decoder is passed

    • getEnum

      default <T extends Enum<T>> T getEnum(String key, Class<T> enumType)
      Gets an enum associated with the given configuration key.
      Type Parameters:
      T - The enum type whose constant is to be returned.
      Parameters:
      enumType - the Class object of the enum type from which to return a constant
      key - The configuration key.
      Returns:
      The associated enum.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a String.
      Since:
      2.8.0

    • getEnum

      default <T extends Enum<T>> T getEnum(String key, Class<T> enumType, T defaultValue)
      Gets the enum associated with the given configuration key. If the key doesn't map to an existing object, the default value is returned.
      Type Parameters:
      T - The enum type whose constant is to be returned.
      Parameters:
      key - The configuration key.
      enumType - the Class object of the enum type from which to return a constant
      defaultValue - The default value.
      Returns:
      The associated enum if key is found and has valid format, default value otherwise.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Enum.
      Since:
      2.8.0

    • getFloat

      float getFloat(String key)
      Gets a float associated with the given configuration key.
      Parameters:
      key - The configuration key.
      Returns:
      The associated float.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Float.

    • getFloat

      float getFloat(String key, float defaultValue)
      Gets a float associated with the given configuration key. If the key doesn't map to an existing object, the default value is returned.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated float.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Float.

    • getFloat

      Float getFloat(String key, Float defaultValue)
      Gets a Float associated with the given configuration key. If the key doesn't map to an existing object, the default value is returned.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated float if key is found and has valid format, default value otherwise.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Float.

    • getInt

      int getInt(String key)
      Gets a int associated with the given configuration key.
      Parameters:
      key - The configuration key.
      Returns:
      The associated int.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Integer.

    • getInt

      int getInt(String key, int defaultValue)
      Gets a int associated with the given configuration key. If the key doesn't map to an existing object, the default value is returned.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated int.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Integer.

    • getInteger

      Integer getInteger(String key, Integer defaultValue)
      Gets an Integer associated with the given configuration key. If the key doesn't map to an existing object, the default value is returned.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated int if key is found and has valid format, default value otherwise.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Integer.

    • getKeys

      Iterator<String> getKeys()
      Gets the list of the keys contained in the configuration. The returned iterator can be used to obtain all defined keys. It does not allow removing elements from this configuration via its remove() method. Note that the keys of this configuration are returned in a form, so that they can be directly evaluated; escaping of special characters (if necessary) has already been performed.
      Returns:
      An Iterator.

    • getKeys

      Iterator<String> getKeys(String prefix)
      Gets the list of the keys contained in the configuration that match the specified prefix. For instance, if the configuration contains the following keys:
      db.user, db.pwd, db.url, window.xpos, window.ypos,
      an invocation of getKeys("db");
      will return the keys below:
      db.user, db.pwd, db.url.
      Note that the prefix itself is included in the result set if there is a matching key. The exact behavior - how the prefix is actually interpreted - depends on a concrete implementation.
      Parameters:
      prefix - The prefix to test against.
      Returns:
      An Iterator of keys that match the prefix.
      See Also:

    • getKeys

      default Iterator<String> getKeys(String prefix, String delimiter)
      Gets the list of the keys contained in the configuration that match the specified prefix. For instance, if the configuration contains the following keys:
      db@user, db@pwd, db@url, window.xpos, window.ypos,
      an invocation of getKeys("db","@");
      will return the keys below:
      db@user, db@pwd, db@url.
      Note that the prefix itself is included in the result set if there is a matching key. The exact behavior - how the prefix is actually interpreted - depends on a concrete implementation.
      Parameters:
      prefix - The prefix to test against.
      delimiter - The prefix delimiter.
      Returns:
      An Iterator of keys that match the prefix.
      Since:
      2.10.0
      See Also:

    • getList

      <T> List<T> getList(Class<T> cls, String key)
      Gets a list of typed objects associated with the given configuration key returning a null if the key doesn't map to an existing object.
      Type Parameters:
      T - the type expected for the elements of the list
      Parameters:
      cls - the class expected for the elements of the list
      key - The configuration key.
      Returns:
      The associated list if the key is found.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not compatible with a list of the specified class.
      Since:
      2.0

    • getList

      <T> List<T> getList(Class<T> cls, String key, List<T> defaultValue)
      Gets a list of typed objects associated with the given configuration key returning the specified default value if the key doesn't map to an existing object. This method recursively retrieves all values stored for the passed in key, i.e. if one of these values is again a complex object like an array or a collection (which may be the case for some concrete subclasses), all values are extracted and added to the resulting list - performing a type conversion if necessary.
      Type Parameters:
      T - the type expected for the elements of the list
      Parameters:
      cls - the class expected for the elements of the list
      key - the configuration key.
      defaultValue - the default value.
      Returns:
      The associated List.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not compatible with a list of the specified class.
      Since:
      2.0

    • getList

      List<Object> getList(String key)
      Gets a List of the values associated with the given configuration key. This method is different from the generic getList() method in that it does not recursively obtain all values stored for the specified property key. Rather, only the first level of the hierarchy is processed. So the resulting list may contain complex objects like arrays or collections - depending on the storage structure used by a concrete subclass. If the key doesn't map to an existing object, an empty List is returned.
      Parameters:
      key - The configuration key.
      Returns:
      The associated List.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a List.

    • getList

      List<Object> getList(String key, List<?> defaultValue)
      Gets a List of strings associated with the given configuration key. If the key doesn't map to an existing object, the default value is returned.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated List of strings.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a List.
      See Also:

    • getLong

      long getLong(String key)
      Gets a long associated with the given configuration key.
      Parameters:
      key - The configuration key.
      Returns:
      The associated long.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Long.

    • getLong

      long getLong(String key, long defaultValue)
      Gets a long associated with the given configuration key. If the key doesn't map to an existing object, the default value is returned.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated long.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Long.

    • getLong

      Long getLong(String key, Long defaultValue)
      Gets a Long associated with the given configuration key. If the key doesn't map to an existing object, the default value is returned.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated long if key is found and has valid format, default value otherwise.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Long.

    • getProperties

      Properties getProperties(String key)
      Gets a list of properties associated with the given configuration key. This method expects the given key to have an arbitrary number of String values, each of which is of the form key=value. These strings are split at the equals sign, and the key parts will become keys of the returned Properties object, the value parts become values.
      Parameters:
      key - The configuration key.
      Returns:
      The associated properties if key is found.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a String/List.
      IllegalArgumentException - if one of the tokens is malformed (does not contain an equals sign).

    • getProperty

      Object getProperty(String key)
      Gets a property from the configuration. This is the most basic get method for retrieving values of properties. In a typical implementation of the Configuration interface the other get methods (that return specific data types) will internally make use of this method. On this level variable substitution is not yet performed. The returned object is an internal representation of the property value for the passed in key. It is owned by the Configuration object. So a caller should not modify this object. It cannot be guaranteed that this object will stay constant over time (i.e. further update operations on the configuration may change its internal state).
      Parameters:
      key - property to retrieve
      Returns:
      the value to which this configuration maps the specified key, or null if the configuration contains no mapping for this key.

    • getShort

      short getShort(String key)
      Gets a short associated with the given configuration key.
      Parameters:
      key - The configuration key.
      Returns:
      The associated short.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Short.

    • getShort

      short getShort(String key, short defaultValue)
      Gets a short associated with the given configuration key.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated short.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Short.

    • getShort

      Short getShort(String key, Short defaultValue)
      Gets a Short associated with the given configuration key. If the key doesn't map to an existing object, the default value is returned.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated short if key is found and has valid format, default value otherwise.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a Short.

    • getString

      String getString(String key)
      Gets a string associated with the given configuration key.
      Parameters:
      key - The configuration key.
      Returns:
      The associated string.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a String.

    • getString

      String getString(String key, String defaultValue)
      Gets a string associated with the given configuration key. If the key doesn't map to an existing object, the default value is returned.
      Parameters:
      key - The configuration key.
      defaultValue - The default value.
      Returns:
      The associated string if key is found and has valid format, default value otherwise.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a String.

    • getStringArray

      String[] getStringArray(String key)
      Gets an array of strings associated with the given configuration key. If the key doesn't map to an existing object an empty array is returned
      Parameters:
      key - The configuration key.
      Returns:
      The associated string array if key is found.
      Throws:
      ConversionException - is thrown if the key maps to an object that is not a String/List of Strings.

    • immutableSubset

      ImmutableConfiguration immutableSubset(String prefix)
      Return a decorator immutable Configuration containing every key from the current Configuration that starts with the specified prefix. The prefix is removed from the keys in the subset. For example, if the configuration contains the following properties: 
          prefix.number = 1
    prefix.string = Apache
    prefixed.foo = bar
    prefix = Jakarta
      the immutable Configuration returned by subset("prefix") will contain the properties: 
          number = 1
    string = Apache
    = Jakarta
      (The key for the value "Jakarta" is an empty string)
      Parameters:
      prefix - The prefix used to select the properties.
      Returns:
      a subset immutable configuration

    • isEmpty

      boolean isEmpty()
      Checks if the configuration is empty.
      Returns:
      true if the configuration contains no property, false otherwise.

    • size

      int size()
      Returns the number of keys stored in this configuration. Note that a concrete implementation is not guaranteed to be efficient; for some implementations it may be expensive to determine the size. Especially, if you just want to check whether a configuration is empty, it is preferable to use the isEmpty() method.
      Returns:
      the number of keys stored in this configuration