Formatting string to get just words in a column

Question

I have a text:

c:\MyMP3s\4 Non Blondes\Bigger!\Faster, More!_Train.mp3

I want to remove form this text these characters: :,\!._ And format the text then like this:

c
MyMP3s
4
Non
Blindes
Bigger
Faster
More
Train
mp3

And write all of this in a file. Here is what I did:

public static void formatText() throws IOException{

    Writer writer = null;
    BufferedReader br = new BufferedReader(new FileReader(new File("File.txt")));

    String line = "";
    while(br.readLine()!=null){
        System.out.println("Into the loop");

        line = br.readLine();
        line = line.replaceAll(":", " ");
        line = line.replaceAll(".", " ");
        line = line.replaceAll("_", " ");

        line = System.lineSeparator();
        System.out.println(line);
        writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("Write.txt")));
        writer.write(line);
    }

And it doesn't work!

The exception:

 Into the loop
Exception in thread "main" java.lang.NullPointerException
    at Application.formatText(Application.java:25)
    at Application.main(Application.java:41)

Answer 1

At the end of your code, you have:

line = System.lineSeperator()

This resets your replacements. Another thing to note is String#replaceAll takes in a regex for the first parameter. So you have to escape any sequences, such as .

String line = "c:\\MyMP3s\\4 Non Blondes\\Bigger!\\Faster, More!_Train.mp3";
System.out.println("Into the loop");

line = line.replaceAll(":\\\\", " ");
line = line.replaceAll("\\.", " ");
line = line.replaceAll("_", " ");
line = line.replaceAll("\\\\", " ");

line = line.replaceAll(" ", System.lineSeparator());

System.out.println(line);

The output is:

Into the loop
c
MyMP3s
4
Non
Blondes
Bigger!
Faster,
More!
Train
mp3