Run nested task in custom task - ant

Question

I have written my own ANT task to perform some function. However, I need this task to invoke a java task as a nest task. So I have the following code in my build file:
<mytask ... >
<java ... />
</mytask>
I would like to run a piece of code after the java task finishes executing but before mytask completes, for the purpose of cleanup.
Is this a broken design, not recommended in build files? If not, which method should I over-ride in order to run the cleanup method?

Answer 1

Let your task implement the org.apache.tools.ant.TaskContainer interface, write your own addTask(Task task) method.
For example (it should only take a task named "java"):
private List<Task> _nestedTask = new ArrayList<>();
public void addTask(Task task) {
if (task.getTaskName().equals("java")) {
_nestedTasks.add(task);
}
else {
throw new BuildException("Support only nested <java> task.");
}
}
Please note that if you write multiple nested <java> tasks in your build file, you need to handle them by your self. To execute the nested <java> tasks, just iterate through the list and call execute() method for each task.
Update:
When a nested task is added, it doesn't run automatically. It won't even run if its execute() method is not called in your custom task.
So... A very basic and simple example:
// your custom task's execute...
public void execute() {
//do something
for (Task task : _nestedTask) {
task.perform(); // here the nested task is executed.
}
//do something
}