elementary java homework?

import java.io.*;
import java.util.*;
import java.util.regex.*;

public class Sample {
public static void main(String[] args) {
try {
if (args.length != 1) {
System.err.println("Usage: java Sample {filename}");
return;
}
Object[] array = read(args[0]);
for (int i = 0; i < array.length; i++)
doJudge((String)array[i]);
} catch (Exception ex) {
ex.printStackTrace();
}
}

private static void doJudge(String line) {
// http://en.wikipedia.org/wiki/Regular_expression
Pattern p0 = Pattern.compile("^0+$");
Matcher m0 = p0.matcher(line);
Pattern p1 = Pattern.compile("^1+$");
Matcher m1 = p1.matcher(line);

if (m0.find()) {
// i want to print out "yes" if all numbers are 0,
System.out.println("yes");
} else if (m1.find()) {
// print out "no" if all numbers are 1,
System.out.println("no");
} else {
// and print out nothing if the numbers are not the same, i.e. some are 0 and some are 1.
}
}

private static Object[] read(String fileName) throws FileNotFoundException, IOException {
BufferedReader reader = new BufferedReader(new FileReader(fileName));
ArrayList<String> list = new ArrayList<String>();
String line = reader.readLine();

while (line != null){
list.add(line);
line = reader.readLine();
}
return list.toArray();
}
}


https://www.youtube.com/watch?v=T-zeKJM5_o0