Remove all blank spaces and empty lines

Question

How to remove all blank spaces and empty lines from a txt File using Java SE?

Input:

qwe
    qweqwe
  qwe



qwe

Output:

Answer 1

...
Scanner scanner = new Scanner(new File("infile.txt"));
PrintStream out = new PrintStream(new File("outfile.txt"));
while(scanner.hasNextLine()){
    String line = scanner.nextLine();
    line = line.trim();
    if(line.length() > 0)
        out.println(line);
}
...