lets research three different code lines:

line 1:
-------

```
    System.out.println(new BufferedReader(new FileReader("data/nio_data.txt")).readLine());

```

output:

```
one

```

line 2:
-------

change `nio_data` with `nio-data`

```
System.out.println(new BufferedReader(new FileReader("data/nio-data.txt")).readLine());

```

output:

```
null

```

line 3:
-------

```
System.out.println(new BufferedReader(new FileReader("data/nioSOMETGING_WRONGdata.txt")).readLine());

```

output:

```
java.io.FileNotFoundException: data\nioSOMETGING_WRONGdata.txt (The system cannot find the file specified)

```

Can you explain this difference?

snippet 2 is very surprising for me.