Property (Apache Ant API)
Description: declaration: package: org.apache.tools.ant.taskdefs, class: Property

Package org.apache.tools.ant.taskdefs

# Class Property

java.lang.Object
org.apache.tools.ant.ProjectComponent
org.apache.tools.ant.Task
org.apache.tools.ant.taskdefs.Property

All Implemented Interfaces:
  `Cloneable`

public class Property extends Task

Sets a property by name, or set of properties (from file or resource) in the project.

Properties are immutable: whoever sets a property first freezes it for the rest of the build; they are most definitely not variable.

There are seven ways to set properties:

- By supplying both the name and value attribute.
- By supplying the name and nested text.
- By supplying both the name and refid attribute.
- By setting the file attribute with the filename of the property file to load. This property file has the format as defined by the file used in the class java.util.Properties.
- By setting the url attribute with the url from which to load the properties. This url must be directed to a file that has the format as defined by the file used in the class java.util.Properties.
- By setting the resource attribute with the resource name of the property file to load. This property file has the format as defined by the file used in the class java.util.Properties.
- By setting the environment attribute with a prefix to use. Properties will be defined for every environment variable by prefixing the supplied name and a period to the name of the variable.
- By setting the runtime attribute with a prefix to use. Properties `prefix.availableProcessors`, `prefix.freeMemory`, `prefix.totalMemory` and `prefix.maxMemory` will be defined with values that correspond to the corresponding methods of the `Runtime` class.

Although combinations of these ways are possible, only one should be used at a time. Problems might occur with the order in which properties are set, for instance.

The value part of the properties being set, might contain references to other properties. These references are resolved at the time these properties are set. This also holds for properties loaded from a property file.

Properties are case sensitive.

Since:
  Ant 1.1

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected Path`
  `classpath`
  `protected String`
  `env`
  `protected File`
  `file`
  `protected String`
  `name`
  `protected String`
  `prefix`
  `protected Reference`
  `ref`
  `protected String`
  `resource`
  `protected URL`
  `url`
  `protected boolean`
  `userProperty`
  `protected String`
  `value`

  ### Fields inherited from class org.apache.tools.ant.Task

  `target, taskName, taskType, wrapper`

  ### Fields inherited from class org.apache.tools.ant.ProjectComponent

  `description, location, project`

- ## Constructor Summary

  Constructors
  Modifier
  Constructor
  Description
  ``
  `Property()`
  Constructor for Property.
  `protected`
  `Property(boolean userProperty)`
  Constructor for Property.
  `protected`
  `Property(boolean userProperty, Project fallback)`
  Constructor for Property.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `protected void`
  `addProperties(Properties props)`
  iterate through a set of properties, resolve them then assign them
  `protected void`
  `addProperty(String n, Object v)`
  add a name value pair to the project property set
  `protected void`
  `addProperty(String n, String v)`
  add a name value pair to the project property set
  `void`
  `addText(String msg)`
  Set a (multiline) property as nested text.
  `Path`
  `createClasspath()`
  The classpath to use when looking up a resource.
  `void`
  `execute()`
  set the property in the project to the value.
  `Path`
  `getClasspath()`
  Get the classpath used when looking up a resource.
  `String`
  `getEnvironment()`
  Get the environment attribute.
  `File`
  `getFile()`
  Get the file attribute.
  `String`
  `getName()`
  Get the property name.
  `String`
  `getPrefix()`
  Get the prefix attribute.
  `boolean`
  `getPrefixValues()`
  Whether to apply the prefix when expanding properties on the right hand side of a properties file as well.
  `Reference`
  `getRefid()`
  Get the refid attribute.
  `String`
  `getResource()`
  Get the resource attribute.
  `String`
  `getRuntime()`
  Get the runtime attribute.
  `URL`
  `getUrl()`
  Get the url attribute.
  `String`
  `getValue()`
  Get the property value.
  `protected void`
  `loadEnvironment(String prefix)`
  load the environment values
  `protected void`
  `loadFile(File file)`
  load properties from a file
  `protected void`
  `loadResource(String name)`
  load properties from a resource in the current classpath
  `protected void`
  `loadRuntime(String prefix)`
  load the runtime values
  `protected void`
  `loadUrl(URL url)`
  load properties from a url
  `void`
  `setBasedir(File basedir)`
  Sets 'basedir' attribute.
  `void`
  `setClasspath(Path classpath)`
  The classpath to use when looking up a resource.
  `void`
  `setClasspathRef(Reference r)`
  the classpath to use when looking up a resource, given as reference to a <path> defined elsewhere
  `void`
  `setEnvironment(String env)`
  Prefix to use when retrieving environment variables.
  `void`
  `setFile(File file)`
  Filename of a property file to load.
  `void`
  `setLocation(File location)`
  Sets the property to the absolute filename of the given file.
  `void`
  `setName(String name)`
  The name of the property to set.
  `void`
  `setPrefix(String prefix)`
  Prefix to apply to properties loaded using `file` or `resource`.
  `void`
  `setPrefixValues(boolean b)`
  Whether to apply the prefix when expanding properties on the right hand side of a properties file as well.
  `void`
  `setRefid(Reference ref)`
  Sets a reference to an Ant datatype declared elsewhere.
  `void`
  `setRelative(boolean relative)`
  Sets 'relative' attribute.
  `void`
  `setResource(String resource)`
  The resource name of a property file to load
  `void`
  `setRuntime(String prefix)`
  Prefix to use when retrieving Runtime properties.
  `void`
  `setUrl(URL url)`
  The url from which to load properties.
  `void`
  `setUserProperty(boolean userProperty)`
  Deprecated.
  since 1.5.x.
  `void`
  `setValue(Object value)`
  Set the value of the property.
  `void`
  `setValue(String value)`
  Set the value of the property as a String.
  `String`
  `toString()`
  get the value of this property

  ### Methods inherited from class org.apache.tools.ant.Task

  `bindToOwner, getOwningTarget, getRuntimeConfigurableWrapper, getTaskName, getTaskType, getWrapper, handleErrorFlush, handleErrorOutput, handleFlush, handleInput, handleOutput, init, isInvalid, log, log, log, log, maybeConfigure, perform, reconfigure, setOwningTarget, setRuntimeConfigurableWrapper, setTaskName, setTaskType`

  ### Methods inherited from class org.apache.tools.ant.ProjectComponent

  `clone, getDescription, getLocation, getProject, setDescription, setLocation, setProject`

  ### Methods inherited from class java.lang.Object

  `equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- ## Field Details

  - ### name

    protected String name

  - ### value

    protected String value

  - ### file

    protected File file

  - ### url

    protected URL url

  - ### resource

    protected String resource

  - ### classpath

    protected Path classpath

  - ### env

    protected String env

  - ### ref

    protected Reference ref

  - ### prefix

    protected String prefix

  - ### userProperty

    protected boolean userProperty

- ## Constructor Details

  - ### Property

    public Property()
    Constructor for Property.

  - ### Property

    protected Property(boolean userProperty)
    Constructor for Property.
    Parameters:
      `userProperty` - if true this is a user property
    Since:
      Ant 1.5

  - ### Property

    protected Property(boolean userProperty, Project fallback)
    Constructor for Property.
    Parameters:
      `userProperty` - if true this is a user property
      `fallback` - a project to use to look for references if the reference is not in the current project
    Since:
      Ant 1.5

- ## Method Details

  - ### setRelative

    public void setRelative(boolean relative)
    Sets 'relative' attribute.
    Parameters:
      `relative` - new value
    Since:
      Ant 1.8.0

  - ### setBasedir

    public void setBasedir(File basedir)
    Sets 'basedir' attribute.
    Parameters:
      `basedir` - new value
    Since:
      Ant 1.8.0

  - ### setName

    public void setName(String name)
    The name of the property to set.
    Parameters:
      `name` - property name

  - ### getName

    public String getName()
    Get the property name.
    Returns:
      the property name

  - ### setLocation

    public void setLocation(File location)
    Sets the property to the absolute filename of the given file. If the value of this attribute is an absolute path, it is left unchanged (with / and \ characters converted to the current platforms conventions). Otherwise it is taken as a path relative to the project's basedir and expanded.
    Parameters:
      `location` - path to set

  - ### setValue

    public void setValue(Object value)
    Set the value of the property.
    Parameters:
      `value` - the value to use.

  - ### setValue

    public void setValue(String value)
    Set the value of the property as a String.
    Parameters:
      `value` - value to assign

  - ### addText

    public void addText(String msg)
    Set a (multiline) property as nested text.
    Parameters:
      `msg` - the text to append to the output text
    Since:
      Ant 1.8.0

  - ### getValue

    public String getValue()
    Get the property value.
    Returns:
      the property value

  - ### setFile

    public void setFile(File file)
    Filename of a property file to load.
    Parameters:
      `file` - filename

  - ### getFile

    public File getFile()
    Get the file attribute.
    Returns:
      the file attribute

  - ### setUrl

    public void setUrl(URL url)
    The url from which to load properties.
    Parameters:
      `url` - url string

  - ### getUrl

    public URL getUrl()
    Get the url attribute.
    Returns:
      the url attribute

  - ### setPrefix

    public void setPrefix(String prefix)
    Prefix to apply to properties loaded using `file` or `resource`. A "." is appended to the prefix if not specified.
    Parameters:
      `prefix` - prefix string
    Since:
      Ant 1.5

  - ### getPrefix

    public String getPrefix()
    Get the prefix attribute.
    Returns:
      the prefix attribute
    Since:
      Ant 1.5

  - ### setPrefixValues

    public void setPrefixValues(boolean b)
    Whether to apply the prefix when expanding properties on the right hand side of a properties file as well.
    Parameters:
      `b` - boolean
    Since:
      Ant 1.8.2

  - ### getPrefixValues

    public boolean getPrefixValues()
    Whether to apply the prefix when expanding properties on the right hand side of a properties file as well.
    Returns:
      boolean
    Since:
      Ant 1.8.2

  - ### setRefid

    public void setRefid(Reference ref)
    Sets a reference to an Ant datatype declared elsewhere. Only yields reasonable results for references PATH like structures or properties.
    Parameters:
      `ref` - reference

  - ### getRefid

    public Reference getRefid()
    Get the refid attribute.
    Returns:
      the refid attribute

  - ### setResource

    public void setResource(String resource)
    The resource name of a property file to load
    Parameters:
      `resource` - resource on classpath

  - ### getResource

    public String getResource()
    Get the resource attribute.
    Returns:
      the resource attribute

  - ### setEnvironment

    public void setEnvironment(String env)
    Prefix to use when retrieving environment variables. Thus if you specify environment="myenv" you will be able to access OS-specific environment variables via property names "myenv.PATH" or "myenv.TERM".

    Note that if you supply a property name with a final "." it will not be doubled. ie environment="myenv." will still allow access of environment variables through "myenv.PATH" and "myenv.TERM". This functionality is currently only implemented on select platforms. Feel free to send patches to increase the number of platforms this functionality is supported on ;).

    Note also that properties are case sensitive, even if the environment variables on your operating system are not, e.g. it will be ${env.Path} not ${env.PATH} on Windows 2000.
    Parameters:
      `env` - prefix

  - ### getEnvironment

    public String getEnvironment()
    Get the environment attribute.
    Returns:
      the environment attribute
    Since:
      Ant 1.5

  - ### setRuntime

    public void setRuntime(String prefix)
    Prefix to use when retrieving Runtime properties.

    Properties `prefix.availableProcessors`, `prefix.freeMemory`, `prefix.totalMemory` and `prefix.maxMemory` will be defined with values that correspond to the corresponding methods of the `Runtime` class.

    Note that if you supply a prefix name with a final "." it will not be doubled. ie runtime="myrt." will still allow access of property through "myrt.availableProcessors" and "myrt.freeMemory".

    The property values are snapshots taken at the point in time when the `property` has been executed.

    Parameters:
      `prefix` - prefix
    Since:
      Ant 1.10.4

  - ### getRuntime

    public String getRuntime()
    Get the runtime attribute.
    Returns:
      the runtime attribute
    Since:
      Ant 1.10.4

  - ### setClasspath

    public void setClasspath(Path classpath)
    The classpath to use when looking up a resource.
    Parameters:
      `classpath` - to add to any existing classpath

  - ### createClasspath

    public Path createClasspath()
    The classpath to use when looking up a resource.
    Returns:
      a path to be configured

  - ### setClasspathRef

    public void setClasspathRef(Reference r)
    the classpath to use when looking up a resource, given as reference to a <path> defined elsewhere
    Parameters:
      `r` - a reference to a classpath

  - ### getClasspath

    public Path getClasspath()
    Get the classpath used when looking up a resource.
    Returns:
      the classpath
    Since:
      Ant 1.5

  - ### setUserProperty

    @Deprecated public void setUserProperty(boolean userProperty)
    Deprecated.
    since 1.5.x. This was never a supported feature and has been deprecated without replacement.
    Parameters:
      `userProperty` - ignored

  - ### toString

    public String toString()
    get the value of this property
    Overrides:
      `toString` in class `Object`
    Returns:
      the current value or the empty string

  - ### execute

    public void execute() throws BuildException
    set the property in the project to the value. if the task was give a file, resource, env or runtime attribute here is where it is loaded
    Overrides:
      `execute` in class `Task`
    Throws:
      `BuildException` - on error

  - ### loadUrl

    protected void loadUrl(URL url) throws BuildException
    load properties from a url
    Parameters:
      `url` - url to load from
    Throws:
      `BuildException` - on error

  - ### loadFile

    protected void loadFile(File file) throws BuildException
    load properties from a file
    Parameters:
      `file` - file to load
    Throws:
      `BuildException` - on error

  - ### loadResource

    protected void loadResource(String name)
    load properties from a resource in the current classpath
    Parameters:
      `name` - name of resource to load

  - ### loadEnvironment

    protected void loadEnvironment(String prefix)
    load the environment values
    Parameters:
      `prefix` - prefix to place before them

  - ### loadRuntime

    protected void loadRuntime(String prefix)
    load the runtime values
    Parameters:
      `prefix` - prefix to place before them
    Since:
      1.10.4

  - ### addProperties

    protected void addProperties(Properties props)
    iterate through a set of properties, resolve them then assign them
    Parameters:
      `props` - the properties to iterate over

  - ### addProperty

    protected void addProperty(String n, String v)
    add a name value pair to the project property set
    Parameters:
      `n` - name of property
      `v` - value to set

  - ### addProperty

    protected void addProperty(String n, Object v)
    add a name value pair to the project property set
    Parameters:
      `n` - name of property
      `v` - value to set
    Since:
      Ant 1.8