Want an eclipse java project to run ant build files automatically

Step 1: Add the build file to your ant view

Click the add button and select the build.xml file from the project. You can also drag the build.xml file onto the ant view (To add the ant view to your perpective, go to Window > Show View > Other…)

Step 2: Run as Ant Build

In your ant view, right click the newly added build file and select Run As > Ant Build… In the dialog window, select the ‘Hide internal targets not selected for execution’ option in the Targets tab. You can rename the builder in the box at the top of the window if you wish (I usually remove the trailing ‘build.xml’. Click Apply and Close.

Step 3: Setup automatic build

Right click on the project, select Properties, then Builders. Click Import. Before closing the screen, highlight the imported build and select edit. Go to the Targets tab select clean for ‘After a clean’ and deploy.local for ‘Auto build’. Apply the changes and close.

Step 4: Enable Auto Build

Go to Project > Build Automatically

source: http://www.simonwhatley.co.uk/using-ant-with-eclipse

Go to your project properties, select "Builders", and add a new Ant Builder. You may specify which targets to run at what time (during a clean, after a clean, etc.), and which resources (if any) to refresh in Eclipse after your ant target is executed.

Project/Builders/New/Ant Builder

There you can add your custom ant build.

At least with Eclipse 4.2 (Juno), the ability to auto-build with Ant has been removed. Under the builder configuration -> "Auto Build", there is a message: "". That said you, can still work around this by:

• Follow the steps above for creating your Ant builder. This will create a file in projectDirectory/.externalToolBuilders.
• Modify projectDirectory/.externalToolBuilders/YourLaunchName.launch:
  • You'll need to add auto, to this line: <stringAttribute key="org.eclipse.ui.externaltools.ATTR_RUN_BUILD_KINDS" value="full,incremental,auto,"/>
  • Specify the target you want run for auto by adding: <stringAttribute key="org.eclipse.ant.ui.ATTR_ANT_AUTO_TARGETS" value="compile-jar,"/>

You can look at your Ant builder configuration and see that everything looks good: