PreferenceModifyListener (Eclipse Platform API Specification)

java.lang.Object
- org.eclipse.core.runtime.preferences.PreferenceModifyListener

```
public abstract class PreferenceModifyListener
extends Object
```
This class provides a hook into the preference service before particular operations on the global preference tree. Preference modify listeners are registered with the preference service via XML and the org.eclipse.equinox.preferences.preferences or the org.eclipse.core.runtime.preferences extension point.
Clients may subclass this type.

Since:

3.1

Constructor Summary

Constructors
Constructor Description

PreferenceModifyListener()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`IEclipsePreferences`	`preApply(IEclipsePreferences node)`	Clients are given the opportunity to modify the given tree before it is applied to the global preference tree.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - PreferenceModifyListener
```
public PreferenceModifyListener()
```
- Method Detail
  - preApply
```
public IEclipsePreferences preApply(IEclipsePreferences node)
```
    Clients are given the opportunity to modify the given tree before it is applied to the global preference tree. Clients should return the tree which should be applied globally. The tree passed in will not be null and clients must not return a null tree.
    This method is called by the preference service from within calls to IPreferencesService.applyPreferences(IExportedPreferences) or IPreferencesService.applyPreferences(IEclipsePreferences, IPreferenceFilter[]).
    
    A typical action for clients to perform would be to intercept the incoming preference tree, migrate old preference values to new ones, and then return the new tree.
    
    Parameters:
    
    node - the tree to modify
    
    Returns:
    
    the tree to apply to the global preferences