Extracting an Interface

See Also

When you use the Extract Interface command, the IDE creates a new interface from the selected public non-static methods in a class or interface. Because an interface does not restrict how its methods are implemented, interfaces can be used in classes that have different functions. Creating interfaces can increase the reusability of your code as you can have multiple classes implementing the same interface. If necessary, you can then modify the interface instead of making modifications in multiple classes.

When you extract an interface, the IDE does the following things:

To extract an interface:

  1. Open the class or interface containing the methods you want to move to an interface.
  2. In the Source editor, right-click in the file and choose Refactor > Extract Interface.

    The Extract Interface dialog box opens.

  3. Type the name for your interface in the Interface Name text field.
  4. In the Members to Extract list, select the members that you want to extract to the new interface.

    If the class from which you are extracting an interface already implements an interface, there is also an item for that implemented interface. If you select the checkbox for that interface, the implements clause for that new interface is moved to the new interface that you are extracting.

  5. If you click Refactor, the IDE applies the changes automatically and skips the remaining steps. If you click Preview, the Refactoring window displays the lines of code that will be changed. Review the list and clear the checkbox of any code that you do not want changed. If the class that you are pushing members from has multiple subclasses and you do not want the members to be pushed to all of them, be sure to clear the checkboxes for the corresponding subclasses. Click Do Refactoring to apply the selected changes.
See Also
Refactoring: Quick Reference
Extracting a Superclass
Extracting a Method
Renaming a Field or Method
Undoing Refactoring Changes

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