Properties

java.lang.Object
- java.util.Dictionary<K,V>
- - java.util.Hashtable<Object,Object>
  - - java.util.Properties

All Implemented Interfaces:

Cloneable, Map<Object,Object>
```
public class Properties
extends Hashtable<Object,Object>
```
A set of persistent properties, which can be saved or loaded from a stream. A property list may also contain defaults, searched if the main list does not contain a property for a given key. An example of a properties file for the german language is given here. This extends the example given in ListResourceBundle. Create a file MyResource_de.properties with the following contents and put it in the CLASSPATH. (The character \u00e4 is the german umlaut)
```
s1=3
s2=MeineDisk
s3=3. M\u00e4rz 96
s4=Die Diskette ''{1}'' enth\u00e4lt {0} in {2}.
s5=0
s6=keine Dateien
s7=1
s8=eine Datei
s9=2
s10={0,number} Dateien
s11=Das Formatieren schlug fehl mit folgender Exception: {0}
s12=FEHLER
s13=Ergebnis
s14=Dialog
s15=Auswahlkriterium
s16=1,3
```
Although this is a sub class of a hash table, you should never insert anything other than strings to this property, or several methods, that need string keys and values, will fail. To ensure this, you should use the get/setProperty method instead of get/put. Properties are saved in ISO 8859-1 encoding, using Unicode escapes with a single u for any character which cannot be represented.
Author:

Jochen Hoenicke, Eric Blake (ebb9@email.byu.edu)

See Also:

PropertyResourceBundle

Nested Class Summary
- Nested classes/interfaces inherited from interface java.util.Map
  Map.Entry<K,V>

Constructor Summary

Constructors
Constructor and Description
`Properties()` Creates a new empty property list with no default values.
`Properties(Properties defaults)` Create a new empty property list with the specified default values.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`String`	`getProperty(String key)` Gets the property with the specified key in this property list.
`String`	`getProperty(String key, String defaultValue)` Gets the property with the specified key in this property list.
`void`	`list(PrintStream out)` Prints the key/value pairs to the given print stream.
`void`	`list(PrintWriter out)` Prints the key/value pairs to the given print writer.
`void`	`load(InputStream inStream)` Reads a property list from the supplied input stream.
`void`	`load(Reader inReader)` Reads a property list from a character stream.
`Enumeration<?>`	`propertyNames()` Returns an enumeration of all keys in this property list, including the keys in the default property list.
`Object`	`setProperty(String key, String value)` Adds the given key/value pair to this properties.
`void`	`store(OutputStream out, String header)` Writes the key/value pairs to the given output stream, in a format suitable for `load`. If header is not null, this method writes a comment containing the header as first line to the stream.

Methods inherited from class java.util.Hashtable
clear, clone, contains, containsKey, containsValue, elements, entrySet, equals, get, hashCode, isEmpty, keys, keySet, put, putAll, remove, size, toString, values

Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - Properties
```
public Properties()
```
    Creates a new empty property list with no default values.
  - Properties
```
public Properties(Properties defaults)
```
    Create a new empty property list with the specified default values.
    
    Parameters:
    
    defaults - a Properties object containing the default values
- Method Detail
  - getProperty
```
public String getProperty(String key)
```
    Gets the property with the specified key in this property list. If the key is not found, the default property list is searched. If the property is not found in the default, null is returned.
    
    Parameters:
    
    key - The key for this property
    
    Returns:
    
    the value for the given key, or null if not found
    
    Throws:
    
    ClassCastException - if this property contains any key or value that isn't a string
    
    See Also:
    
    defaults, setProperty(String, String), getProperty(String, String)
  - getProperty
```
public String getProperty(String key,
                          String defaultValue)
```
    Gets the property with the specified key in this property list. If the key is not found, the default property list is searched. If the property is not found in the default, the specified defaultValue is returned.
    
    Parameters:
    
    key - The key for this property
    
    defaultValue - A default value
    
    Returns:
    
    The value for the given key
    
    Throws:
    
    ClassCastException - if this property contains any key or value that isn't a string
    
    See Also:
    
    defaults, setProperty(String, String)
  - list
```
public void list(PrintStream out)
```
    Prints the key/value pairs to the given print stream. This is mainly useful for debugging purposes.
    
    Parameters:
    
    out - the print stream, where the key/value pairs are written to
    
    Throws:
    
    ClassCastException - if this property contains a key or a value that isn't a string
    
    See Also:
    
    list(PrintWriter)
  - list
```
public void list(PrintWriter out)
```
    Prints the key/value pairs to the given print writer. This is mainly useful for debugging purposes.
    
    Parameters:
    
    out - the print writer where the key/value pairs are written to
    
    Throws:
    
    ClassCastException - if this property contains a key or a value that isn't a string
    
    Since:
    
    1.1
    
    See Also:
    
    list(PrintStream)
  - load
```
public void load(InputStream inStream)
          throws IOException
```
    Reads a property list from the supplied input stream. This method has the same functionality as load(Reader) but the character encoding is assumed to be ISO-8859-1. Unicode characters not within the Latin1 set supplied by ISO-8859-1 should be escaped using '\\uXXXX' where XXXX is the UTF-16 code unit in hexadecimal.
    
    Parameters:
    
    inStream - the byte stream to read the property list from.
    
    Throws:
    
    IOException - if an I/O error occurs.
    
    Since:
    
    1.2
    
    See Also:
    
    load(Reader)
  - load
```
public void load(Reader inReader)
          throws IOException
```
    Reads a property list from a character stream. The stream should have the following format:
    An empty line or a line starting with # or ! is ignored. An backslash (\) at the end of the line makes the line continueing on the next line (but make sure there is no whitespace after the backslash). Otherwise, each line describes a key/value pair.
    The chars up to the first whitespace, = or : are the key. You can include this caracters in the key, if you precede them with a backslash (\). The key is followed by optional whitespaces, optionally one = or :, and optionally some more whitespaces. The rest of the line is the resource belonging to the key.
    Escape sequences \t, \n, \r, \\, \", \', \!, \#, \ (a space), and unicode characters with the \\uxxxx notation are detected, and converted to the corresponding single character.
```
# This is a comment
key     = value
k\:5      \ a string starting with space and ending with newline\n
# This is a multiline specification; note that the value contains
# no white space.
weekdays: Sunday,Monday,Tuesday,Wednesday,\\
          Thursday,Friday,Saturday
# The safest way to include a space at the end of a value:
label   = Name:\\u0020
```
    Parameters:
    
    inReader - the input Reader.
    
    Throws:
    
    IOException - if an error occurred when reading the input
    
    NullPointerException - if in is null
    
    Since:
    
    1.6
  - propertyNames
```
public Enumeration<?> propertyNames()
```
    Returns an enumeration of all keys in this property list, including the keys in the default property list.
    
    Returns:
    
    an Enumeration of all defined keys
  - setProperty
```
public Object setProperty(String key,
                          String value)
```
    Adds the given key/value pair to this properties. This calls the hashtable method put.
    
    Parameters:
    
    key - the key for this property
    
    value - the value for this property
    
    Returns:
    
    The old value for the given key
    
    Since:
    
    1.2
    
    See Also:
    
    getProperty(String)
  - store
```
public void store(OutputStream out,
                  String header)
           throws IOException
```
    Writes the key/value pairs to the given output stream, in a format suitable for load.
    If header is not null, this method writes a comment containing the header as first line to the stream. The next line (or first line if header is null) contains a comment with the current date. Afterwards the key/value pairs are written to the stream in the following format.
    Each line has the form key = value. Newlines, Returns and tabs are written as \n,\t,\r resp. The characters \, !, #, = and : are preceeded by a backslash. Spaces are preceded with a backslash, if and only if they are at the beginning of the key. Characters that are not in the ascii range 33 to 127 are written in the \uxxxx Form.
    Following the listing, the output stream is flushed but left open.
    
    Parameters:
    
    out - the output stream
    
    header - the header written in the first line, may be null
    
    Throws:
    
    ClassCastException - if this property contains any key or value that isn't a string
    
    IOException - if writing to the stream fails
    
    NullPointerException - if out is null
    
    Since:
    
    1.2

Class Properties

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.Map

Constructor Summary

Method Summary

Methods inherited from class java.util.Hashtable

Methods inherited from class java.lang.Object

Constructor Detail

Properties

Properties

Method Detail

getProperty

getProperty

list

list

load

load

propertyNames

setProperty

store