# Class Properties

java.lang.Object
java.util.AbstractMap<String,String>
java.util.HashMap<String,String>
com.codename1.io.Properties

All Implemented Interfaces:
  `Map<String,String>`

public class Properties extends HashMap<String,String>

A `Properties` object is a `Hashtable` where the keys and values must be `String`s. Each property can have a default `Properties` list which specifies the default values to be used when a given key is not found in this `Properties` instance.

Character Encoding

Note that in some cases `Properties` uses ISO-8859-1 instead of UTF-8. ISO-8859-1 is only capable of representing a tiny subset of Unicode. Use either the `loadFromXML`/`storeToXML` methods (which use UTF-8 by default) or the `load`/`store` overloads that take an `OutputStreamWriter` (so you can supply a UTF-8 instance) instead.

##### See also

- Hashtable

- java.lang.System#getProperties

- ## Nested Class Summary

  ### Nested classes/interfaces inherited from class AbstractMap

  `AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>`

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected Properties`
  `defaults`
  The default values for keys not found in this `Properties` instance.

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `Properties()`
  Constructs a new `Properties` object.
  `Properties(Properties properties)`
  Constructs a new `Properties` object using the specified default `Properties`.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `String`
  `getProperty(String name)`
  Searches for the property with the specified name.
  `String`
  `getProperty(String name, String defaultValue)`
  Searches for the property with the specified name.
  `void`
  `load(InputStream in)`
  Loads properties from the specified `InputStream`, assumed to be ISO-8859-1.
  `void`
  `load(Reader in)`
  Loads properties from the specified `Reader`.
  `Enumeration<?>`
  `propertyNames()`
  Returns all of the property names (keys) in this `Properties` object.
  `void`
  `save(OutputStream out, String comment)`
  Deprecated.
  This method ignores any `IOException` thrown while writing -- use `#store` instead for better exception handling.
  `Object`
  `setProperty(String name, String value)`
  Maps the specified key to the specified value.
  `void`
  `store(OutputStream out, String comment)`
  Stores properties to the specified `OutputStream`, using ISO-8859-1.
  `void`
  `store(Writer writer, String comment)`
  Stores the mappings in this `Properties` object to `out`, putting the specified comment at the beginning.
  `Set<String>`
  `stringPropertyNames()`
  Returns those property names (keys) in this `Properties` object for which both key and value are strings.

  ### Methods inherited from class HashMap

  `clear, containsKey, containsValue, entrySet, get, isEmpty, keySet, put, putAll, remove, size, values`

  ### Methods inherited from class AbstractMap

  `equals, hashCode, toString`

  ### Methods inherited from class Object

  `clone, getClass, notify, notifyAll, wait, wait, wait`

  ### Methods inherited from interface Map

  `compute, computeIfAbsent, computeIfPresent, equals, forEach, getOrDefault, hashCode, merge, putIfAbsent, remove, replace, replace, replaceAll`

- ## Field Details

  - ### defaults

    protected Properties defaults
    The default values for keys not found in this `Properties` instance.

- ## Constructor Details

  - ### Properties

    public Properties()
    Constructs a new `Properties` object.

  - ### Properties

    public Properties(Properties properties)

    Constructs a new `Properties` object using the specified default `Properties`.

    ###### Parameters

    - `properties`: the default `Properties`.

- ## Method Details

  - ### getProperty

    public String getProperty(String name)

    Searches for the property with the specified name. If the property is not found, the default `Properties` are checked. If the property is not found in the default `Properties`, `null` is returned.

    ###### Parameters

    - `name`: the name of the property to find.

    ###### Returns

    the named property value, or `null` if it can't be found.

  - ### getProperty

    public String getProperty(String name, String defaultValue)

    Searches for the property with the specified name. If the property is not found, it looks in the default `Properties`. If the property is not found in the default `Properties`, it returns the specified default.

    ###### Parameters

    - `name`: the name of the property to find.

    - `defaultValue`: the default value.

    ###### Returns

    the named property value.

  - ### load

    public void load(InputStream in) throws IOException

    Loads properties from the specified `InputStream`, assumed to be ISO-8859-1. See "Character Encoding".

    ###### Parameters

    - `in`: the `InputStream`

    ###### Throws

    - `IOException`
    Throws:
      `IOException`

  - ### load

    public void load(Reader in) throws IOException

    Loads properties from the specified `Reader`. The properties file is interpreted according to the following rules:

    - Empty lines are ignored.

    - Lines starting with either a "#" or a "!" are comment lines and are ignored.

    - A backslash at the end of the line escapes the following newline character ("\r", "\n", "\r\n"). If there's whitespace after the backslash it will just escape that whitespace instead of concatenating the lines. This does not apply to comment lines.

    - A property line consists of the key, the space between the key and the value, and the value. The key goes up to the first whitespace, "=" or ":" that is not escaped. The space between the key and the value contains either one whitespace, one "=" or one ":" and any amount of additional whitespace before and after that character. The value starts with the first character after the space between the key and the value.

    - Following escape sequences are recognized: `\` , `\\`, `\r`, `\n`, `\!`, `\#`, `\t`, `\b`, `\f`, and `` (unicode character).

    ###### Parameters

    - `in`: the `Reader`

    ###### Throws

    - `IOException`

    ###### Since

    1.6

    Throws:
      `IOException`

  - ### propertyNames

    public Enumeration<?> propertyNames()
    Returns all of the property names (keys) in this `Properties` object.

  - ### stringPropertyNames

    public Set<String> stringPropertyNames()

    Returns those property names (keys) in this `Properties` object for which both key and value are strings.

    ###### Returns

    a set of keys in the property list

    ###### Since

    1.6

  - ### save

    @Deprecated public void save(OutputStream out, String comment)
    Deprecated.
    This method ignores any `IOException` thrown while writing -- use `#store` instead for better exception handling.

    Saves the mappings in this `Properties` to the specified `OutputStream`, putting the specified comment at the beginning. The output from this method is suitable for being read by the `#load(InputStream)` method.

    ###### Parameters

    - `out`: the `OutputStream` to write to.

    - `comment`: the comment to add at the beginning.

    ###### Throws

    - `ClassCastException`: @throws ClassCastException if the key or value of a mapping is not a String.

    ###### Deprecated

  - ### setProperty

    public Object setProperty(String name, String value)

    Maps the specified key to the specified value. If the key already exists, the old value is replaced. The key and value cannot be `null`.

    ###### Parameters

    - `name`: the key.

    - `value`: the value.

    ###### Returns

    the old value mapped to the key, or `null`.

  - ### store

    public void store(OutputStream out, String comment) throws IOException

    Stores properties to the specified `OutputStream`, using ISO-8859-1. See "Character Encoding".

    ###### Parameters

    - `out`: the `OutputStream`

    - `comment`: an optional comment to be written, or null

    ###### Throws

    - `IOException`

    - `ClassCastException`: if a key or value is not a string

    Throws:
      `IOException`

  - ### store

    public void store(Writer writer, String comment) throws IOException

    Stores the mappings in this `Properties` object to `out`, putting the specified comment at the beginning.

    ###### Parameters

    - `writer`: the `Writer`

    - `comment`: an optional comment to be written, or null

    ###### Throws

    - `IOException`

    - `ClassCastException`: if a key or value is not a string

    ###### Since

    1.6

    Throws:
      `IOException`