nested progress tasks into one progressbar javafx - javafx

Question

Is it possible to render in one progressbar the progress of 2 nested tasks?
I mean, if I have to read lines from several files in several directories. I have this snippet code:
EDIT:
final int steps = directories.size();
Task<Integer> task2 = new Task<Integer>() {
/**
*/
#Override
protected Integer call() throws Exception {
int len = files.length;
updateProgress(0, len);
for(int i = 0; i < files.length; i++) {
final String filename = files[i].getName();
final String file = files[i].getPath();
try {
BufferedReader br = new BufferedReader(new FileReader(file));
}
String currentLine = null;
while ((currentLine = br.readLine()) != null) {
readlines(currentLine, filename);
}
} catch (IOException xs) {
xs.getMessage();
}
System.out.println("******* Working on: " + file + " ******************************");
updateProgress(i + 1, files.length);
}
System.out.println("done: " + directoryName);
return len;
}
};
task2.setOnRunning(r -> {
DoubleBinding totalProgress = null;
for(int i = 0; i < steps; i++) {
DoubleBinding increment = task2.progressProperty().divide(steps);
if (totalProgress == null) {
totalProgress = increment;
} else {
totalProgress = totalProgress.add(increment);
}
}
progressBar.progressProperty().bind(totalProgress);
status.textProperty().bind(task2.stateProperty().asString());
statusProcess.textProperty().bind(Bindings.when(totalProgress.isEqualTo(-1))
.then("0.00")
.otherwise(task2.progressProperty().multiply(100.00).asString("%.02f %%")));
console.textProperty().bind(task2.messageProperty());
});
new Thread(task2).start();
I am enable to access progress bar but as long as I have directories, the progress bar will restart to 0 and will check for files into the next directory and then populate the progress bar until 1 and then restart to 0 if there is another directory.
How can I do if I want to display these 2 tasks in one as I don't want to restart from 0 when the next directory is reading. If I have for example 4 directories, I expect to see a moving the progressbar until its quarter and so on.
Is anybody as an idea what I am doing wrong?

Answer 1

You can do something like
progressBar.progressProperty().bind(Bindings.createDoubleBinding(
() -> Math.max(0, task1.getProgress()) / 2 + Math.max(0, task2.getProgress()) /2 ,
task1.progressProperty(), task2.progressProperty());
If you can easily estimate or compute the relative times each task will take, you can weight the progress of each task accordingly, instead of simply averaging them as in the code above.