### Saving & Reusing Ant options

When we ran the HelloWorld.xml Ant buildfile in the last section, the choice of targets, along with all other options in the Run Ant dialog were saved in an entity called a 'launch configuration'. Launch configurations contain all details necessary to run a single Ant buildfile in a particular way. It is perfectly valid to have multiple launch configurations associated with a single Ant buildfile. So, in addition to the launch configuration that was created in the last step, specifying that our HelloWorld.xml buildfile should execute the targets Hello & World in that order, we could create a second launch configuration for this same buildfile specifying the same targets but in the reverse order. So far so good. But the really nice thing about launch configurations is that now you can quickly run your Ant buildfile in either configuration by simply specifying the corresponding launch configuration.

1. From the Workbench toolbar, select Run > External Tools > External Tools....
2. The External Tools dialog opens and presents a choice of launch configurations to view and edit. The launch configuration we created when we ran the HelloWorld.xml buildfile is selected in the tree at the left, and the tabs on the right show the options for this launch configuration.
3. At the top of the dialog, change the Name to 'Hello World' and Apply the change.
4. In the tree at left, bring up on the context menu on the selected launch configuration and choose Duplicate. A copy of the launch configuration for the Hello World buildfile is created, '(1)' is appended to the name, and the new launch configuration is selected in the tree.
5. Rename the new configuration to 'World Hello'.
6. In the Targets tab, click the Order... button, change the order of the targets so that the World target executes first, and Apply the change.
7. Click Run.
8. As before, the HelloWorld.xml buildfile runs and sends its output to the Console view. This time however, because the targets were reversed, the output is reversed as well.
9. Go back to the External Tools drop down in the toolbar.
   Notice now that there are two entries in the history, one for Hello World and one for World Hello. In order to rerun the Ant buildfile so that it outputs Hello World, just select this launch configuration in the history. To rerun the launch configuration that outputs World Hello, select this configuration in the history.
   Note: The history is ordered so that the most frequently run configurations are at the top of the dropdown.

This concludes our quick look at the basics of Ant integration in Eclipse. In the next chapters, we consider several real-world use cases for running Ant buildfiles inside Eclipse.