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## org.eclipse.ui.contexts
Interface IContext

All Superinterfaces:
  Comparable

public interface IContext
extends Comparable

An instance of this interface is an context as defined by the extension point `org.eclipse.ui.contexts`.

An instance of this interface can be obtained from an instance of `IContextManager` for any identifier, whether or not an context with that identifier is defined in the extension registry.

The handle-based nature of this API allows it to work well with runtime plugin activation and deactivation. If a context is defined, that means that its corresponding plug-in is active. If the plug-in is then deactivated, the context will still exist but it will be undefined. An attempts to use an undefined context will result in a `NotDefinedException` being thrown.

This interface is not intended to be extended or implemented by clients.

Since:
  3.0
See Also:
  `IContextManager`

Method Summary
`void` | `addContextListener(IContextListener contextListener)` Registers an instance of `IContextListener` to listen for changes to properties of this instance.
`String` | `getId()` Returns the identifier of this instance.
`String` | `getName()` Returns the name of this instance suitable for display to the user.
`String` | `getParentId()` Returns the identifier of the parent of this instance.
`boolean` | `isDefined()` Returns whether or not this instance is defined.
`boolean` | `isEnabled()` Returns whether or not this instance is enabled.
`void` | `removeContextListener(IContextListener contextListener)` Unregisters an instance of `IContextListener` listening for changes to properties of this instance.

Methods inherited from interface java.lang.Comparable
`compareTo`

Method Detail

### addContextListener

    public void addContextListener(IContextListener contextListener)

  Registers an instance of `IContextListener` to listen for changes to properties of this instance.

  Parameters:
    `contextListener` - the instance to register. Must not be `null`. If an attempt is made to register an instance which is already registered with this instance, no operation is performed.

### getId

    public String getId()

  Returns the identifier of this instance.

  Returns:
    the identifier of this instance. Guaranteed not to be `null`.

### getName

    public String getName()
                   throws NotDefinedException

  Returns the name of this instance suitable for display to the user.

  Notification is sent to all registered listeners if this property changes.

  Returns:
    the name of this instance. Guaranteed not to be `null`.
  Throws:
    `NotDefinedException` - if this instance is not defined.

### getParentId

    public String getParentId()
                       throws NotDefinedException

  Returns the identifier of the parent of this instance.

  Notification is sent to all registered listeners if this property changes.

  Returns:
    the identifier of the parent of this instance. May be `null`.
  Throws:
    `NotDefinedException` - if this instance is not defined.

### isDefined

    public boolean isDefined()

  Returns whether or not this instance is defined.

  Notification is sent to all registered listeners if this property changes.

  Returns:
    true, iff this instance is defined.

### isEnabled

    public boolean isEnabled()

  Returns whether or not this instance is enabled.

  Notification is sent to all registered listeners if this property changes.

  Returns:
    true, iff this instance is enabled.

### removeContextListener

    public void removeContextListener(IContextListener contextListener)

  Unregisters an instance of `IContextListener` listening for changes to properties of this instance.

  Parameters:
    `contextListener` - the instance to unregister. Must not be `null`. If an attempt is made to unregister an instance which is not already registered with this instance, no operation is performed.

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