org.apache.tools.ant.util

Class LayoutPreservingProperties

public class LayoutPreservingProperties extends Properties

A Properties collection which preserves comments and whitespace present in the input stream from which it was loaded.

The class defers the usual work of the java.util.Properties class to there, but it also keeps track of the contents of the input stream from which it was loaded (if applicable), so that it can write out the properties in as close a form as possible to the input.

If no changes occur to property values, the output should be the same as the input, except for the leading date stamp, as normal for a properties file. Properties added are appended to the file. Properties whose values are changed are changed in place. Properties that are removed are excised. If the removeComments flag is set, then the comments immediately preceding the property are also removed.

If a second set of properties is loaded into an existing set, the lines of the second set are added to the end. Note however, that if a property already stored is present in a stream subsequently loaded, then that property is removed before the new value is set. For example, consider the file

 # the first line
 alpha=one

 # the second line
 beta=two

This file is loaded, and then the following is also loaded into the same LayoutPreservingProperties object

 # association
 beta=band

 # and finally
 gamma=rays

The resulting collection sequence of logical lines depends on whether or not removeComments was set at the time the second stream is loaded. If it is set, then the resulting list of lines is

 # the first line
 alpha=one

 # association
 beta=band

 # and finally
 gamma=rays

If the flag is not set, then the comment "the second line" is retained, although the key-value pair beta=two is removed.

Constructor Summary
LayoutPreservingProperties()
Create a new, empty, Properties collection, with no defaults.
LayoutPreservingProperties(Properties defaults)
Create a new, empty, Properties collection, with the specified defaults.
Method Summary
voidclear()
Objectclone()
booleanisRemoveComments()
Returns true if comments are removed along with properties, or false otherwise.
voidlistLines(PrintStream out)
Echo the lines of the properties (including blanks and comments) to the stream.
voidload(InputStream inStream)
Objectput(Object key, Object value)
Objectremove(Object key)
voidsaveAs(File dest)
Save the properties to a file.
ObjectsetProperty(String key, String value)
voidsetRemoveComments(boolean val)
Sets the behaviour for comments accompanying properties that are being removed.
voidstore(OutputStream out, String header)

Constructor Detail

LayoutPreservingProperties

public LayoutPreservingProperties()
Create a new, empty, Properties collection, with no defaults.

LayoutPreservingProperties

public LayoutPreservingProperties(Properties defaults)
Create a new, empty, Properties collection, with the specified defaults.

Parameters: defaults the default property values

Method Detail

clear

public void clear()

clone

public Object clone()

isRemoveComments

public boolean isRemoveComments()
Returns true if comments are removed along with properties, or false otherwise. If true, then when a property is removed, the comment preceding it in the original file is removed also.

Returns: true if leading comments are removed when a property is removed; false otherwise

listLines

public void listLines(PrintStream out)
Echo the lines of the properties (including blanks and comments) to the stream.

Parameters: out the stream to write to

load

public void load(InputStream inStream)

put

public Object put(Object key, Object value)

remove

public Object remove(Object key)

saveAs

public void saveAs(File dest)
Save the properties to a file.

Parameters: dest the file to write to

setProperty

public Object setProperty(String key, String value)

setRemoveComments

public void setRemoveComments(boolean val)
Sets the behaviour for comments accompanying properties that are being removed. If true, then when a property is removed, the comment preceding it in the original file is removed also.

Parameters: val true if leading comments are to be removed when a property is removed; false otherwise

store

public void store(OutputStream out, String header)