class FileException inherits Exception { ... };
class BadFormatException inherits FileException { ... };
class IOException inherits Exception { ... };

// main code...
//
try {
    readDataFromFile( "file.dat" );
} catch ( FileException e ) {
    System.out.println("Something went wrong");
}

int readDataFromFile( String filename ) throws FileException {
// ...
    fileRef = openFile( filename );
    while ( data = readLine( fileRef ) ) {
        ...
    }
}

File openFile( String filename ) throws IOException { ... }

String readLine( File file ) throws BadFormatException { ... }