Interface Line

All Superinterfaces:
AutoCloseable
All Known Subinterfaces:
Clip, DataLine, Mixer, Port, SourceDataLine, TargetDataLine
public interface Line extends AutoCloseable
The Line interface represents a mono or multi-channel audio feed. A line is an element of the digital audio "pipeline," such as a mixer, an input or output port, or a data path into or out of a mixer.

A line can have controls, such as gain, pan, and reverb. The controls themselves are instances of classes that extend the base Control class. The Line interface provides two accessor methods for obtaining the line's controls: getControls returns the entire set, and getControl returns a single control of specified type.

Lines exist in various states at different times. When a line opens, it reserves system resources for itself, and when it closes, these resources are freed for other objects or applications. The isOpen() method lets you discover whether a line is open or closed. An open line need not be processing data, however. Such processing is typically initiated by subinterface methods such as SourceDataLine.write and TargetDataLine.read.

You can register an object to receive notifications whenever the line's state changes. The object must implement the LineListener interface, which consists of the single method update. This method will be invoked when a line opens and closes (and, if it's a DataLine , when it starts and stops).

An object can be registered to listen to multiple lines. The event it receives in its update method will specify which line created the event, what type of event it was (OPEN, CLOSE, START, or STOP), and how many sample frames the line had processed at the time the event occurred.

Since:
1.3
See Also:

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Interface
    Description
    static class 
    Line.Info
    A Line.Info object contains information about a line.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    addLineListener(LineListener listener)
    Adds a listener to this line.
    void
    close()
    Closes the line, indicating that any system resources in use by the line can be released.
    Control
    getControl(Control.Type control)
    Obtains a control of the specified type, if there is any.
    Control[]
    getControls()
    Obtains the set of controls associated with this line.
    Line.Info
    getLineInfo()
    Obtains the Line.Info object describing this line.
    boolean
    isControlSupported(Control.Type control)
    Indicates whether the line supports a control of the specified type.
    boolean
    isOpen()
    Indicates whether the line is open, meaning that it has reserved system resources and is operational, although it might not currently be playing or capturing sound.
    void
    open()
    Opens the line, indicating that it should acquire any required system resources and become operational.
    void
    removeLineListener(LineListener listener)
    Removes the specified listener from this line's list of listeners.

  • Method Details

    • getLineInfo

      Line.Info getLineInfo()
      Obtains the Line.Info object describing this line.
      Returns:
      description of the line

    • open

      void open() throws LineUnavailableException
      Opens the line, indicating that it should acquire any required system resources and become operational. If this operation succeeds, the line is marked as open, and an OPEN event is dispatched to the line's listeners.

      Note that some lines, once closed, cannot be reopened. Attempts to reopen such a line will always result in an LineUnavailableException.

      Some types of lines have configurable properties that may affect resource allocation. For example, a DataLine must be opened with a particular format and buffer size. Such lines should provide a mechanism for configuring these properties, such as an additional open method or methods which allow an application to specify the desired settings.

      This method takes no arguments, and opens the line with the current settings. For SourceDataLine and TargetDataLine objects, this means that the line is opened with default settings. For a Clip, however, the buffer size is determined when data is loaded. Since this method does not allow the application to specify any data to load, an IllegalArgumentException is thrown. Therefore, you should instead use one of the open methods provided in the Clip interface to load data into the Clip.

      For DataLine's, if the DataLine.Info object which was used to retrieve the line, specifies at least one fully qualified audio format, the last one will be used as the default format.

      Throws:
      IllegalArgumentException - if this method is called on a Clip instance
      LineUnavailableException - if the line cannot be opened due to resource restrictions
      See Also:

    • close

      void close()
      Closes the line, indicating that any system resources in use by the line can be released. If this operation succeeds, the line is marked closed and a CLOSE event is dispatched to the line's listeners.
      Specified by:
      close in interface AutoCloseable
      See Also:

    • isOpen

      boolean isOpen()
      Indicates whether the line is open, meaning that it has reserved system resources and is operational, although it might not currently be playing or capturing sound.
      Returns:
      true if the line is open, otherwise false
      See Also:

    • getControls

      Control[] getControls()
      Obtains the set of controls associated with this line. Some controls may only be available when the line is open. If there are no controls, this method returns an array of length 0.
      Returns:
      the array of controls
      See Also:

    • isControlSupported

      boolean isControlSupported(Control.Type control)
      Indicates whether the line supports a control of the specified type. Some controls may only be available when the line is open.
      Parameters:
      control - the type of the control for which support is queried
      Returns:
      true if at least one control of the specified type is supported, otherwise false

    • getControl

      Control getControl(Control.Type control)
      Obtains a control of the specified type, if there is any. Some controls may only be available when the line is open.
      Parameters:
      control - the type of the requested control
      Returns:
      a control of the specified type
      Throws:
      IllegalArgumentException - if a control of the specified type is not supported
      See Also:

    • addLineListener

      void addLineListener(LineListener listener)
      Adds a listener to this line. Whenever the line's status changes, the listener's update() method is called with a LineEvent object that describes the change.
      Parameters:
      listener - the object to add as a listener to this line
      See Also:

    • removeLineListener

      void removeLineListener(LineListener listener)
      Removes the specified listener from this line's list of listeners.
      Parameters:
      listener - listener to remove
      See Also: