Can you execute an Ant task from within a custom Ant task? - ant

Question

I am writing a custom Ant task to handle some business logic, and I want to call the Move Ant task.
I presume I would use the Execute java class, but I'm having trouble figuring it out.
Am I going in the right direction, or can you not call one class from another in an Ant way?

Answer 1

For your task, you wanna call the Move task. So you want to move some files.
Generally, when you are coding in Java, you should avoid calling built-in Ant tasks, as they usually have poor performance. For example, you can either use File.renameTo() method from java.io.File or Files.move() from java.nio.file.Files (JDK7 only).
If you do want to take advantage of some Ant things, like <fileset>, you may want your task to be able to take Move task as a nested task in build xml. Just make your task a TaskContainer and do some filtering in its method.
Of course, you can also just import the Move task, set all the needed properties, and the call its execute() method. But I do not like that.

Answer 2

The above answer does not answer the original question "Can you execute an Ant task from within a custom Ant task?"
The answer is definitely yes.
Here is an example with Copy. Move is similar. And while File.renameTo() may have better performance than calling an Ant Move task, there are definitely reasons why you might want to invoke an Ant task from within a custom Ant task, especially in cases where no suitable JRE alternative exists. The Ant API is very extensive and provides a great number of useful tasks. Furthermore, you may want invoke a custom Ant task from within a different custom Ant task.
See also http://www.jajakarta.org/ant/ant-1.6.1/docs/ja/manual/api/org/apache/tools/ant/taskdefs/package-summary.html
import org.apache.tools.ant.types.FileSet;
import org.apache.tools.ant.taskdefs.Copy;
...
// set up the Strings inputPath and outputPath appropriately...
...
try{
FileSet inputSet = new FileSet(); // what to copy FROM
inputSet.setDir(new File(inputPath));
Copy copyTask = new Copy();
copyTask.setProject(getProject());
copyTask.setTodir(outputPath); // where to copy TO
copyTask.setFailOnError(true);
copyTask.addFileset(inputSet);
copyTask.execute();
}
catch(Exception e){
String msg = "Exception while invoking Copy task with inputPath=\"" + inputPath + "\" and outputPath=\"" + outputPath + "\": " + e.toString();
throw new BuildException(msg, e);
}