In my school assignment, we are tasked with using threads to speed up a file searching algorithm. The original program they gave us was this:
package filefinder;
import java.io.File;
import java.io.IOException;
public class FileFinder {
private final File rootDir;
public FileFinder(String root) throws IOException {
rootDir = new File(root);
if (!(rootDir.exists() && rootDir.isDirectory())) {
throw new IOException(root + " is not a directory");
}
}
public void findFile(String file) {
find(rootDir, file);
}
private void find(File rootDir, String fileName) {
File[] files = rootDir.listFiles();
if (files != null) {
for (File file : files) {
if (file.getName().equals(fileName)) {
System.out.println("Found at: " + file.getAbsolutePath());
} else if (file.isDirectory()) {
find(file, fileName);
}
}
}
}
}
Which is called in the main file:
package filefinder;
import java.io.IOException;
public class Main {
public static void main(String[] args) {
try {
String goal = "needle.txt";
String root = "haystack";
FileFinder ff = new FileFinder(root);
ff.findFile(goal);
} catch (IOException e) {
e.printStackTrace();
}
}
}
This finds the file. Then, to run it with threads, I tried to split it into 5 threads, 1 for each of the 5 subdirectories.
package filefinder;
import java.io.IOException;
import java.io.File;
public class Main {
public static void main(String[] args) {
try {
String goal = "needle.txt";
String root = "haystack";
File file = new File(root);
File[] children = file.listFiles();
System.out.println(children);
for (File child : children)
{
if (child.isDirectory()){
new FileFinder(child.getName());}
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
Yet now, it throws the exception "haystack1 is not a directory". Why is it not able to find the subdirectories this way? Thank you.
I did managed to run it with threads, but it didn't improve performances at all. A classmate of mine said it was because I defined a new thread during each iteration of the for-loop, which is why here I'm trying to just create a new thread for each of the direct subdirectories, so the 5 folders inside of the main folder.
The folder we're searching through is called 'haystack', containing 5 folders called 'heystack1' to 'heystack5', each with the same 5 folders until a certain point.
