The code can be simplified and improved in several ways, and the inner loop can be made tighter. Let me show you how:
private static List<List<String>> readTXTFile(String csvFileName) throws IOException {
String line = null;
BufferedReader stream = null;
List<List<String>> csvData = new ArrayList<List<String>>();
try {
stream = new BufferedReader(new FileReader(csvFileName));
while ((line = stream.readLine()) != null) {
String[] splitted = line.split(",");
List<String> dataLine = new ArrayList<String>(splitted.length);
for (String data : splitted)
dataLine.add(data);
csvData.add(dataLine);
}
} finally {
if (stream != null)
stream.close();
}
return csvData;
}
- A method should throw an exception as specific as possible, here it's better to use
IOException instead of simply Exception
- Whenever possible, return interface types instead of concrete classes. Using
List is preferred to using Vector, this allows you the flexibility to change the implementation of the collection later
- Talking about collections:
Vector is thread-safe and synchronized in many of its public methods, that can cause a performance hit. If you don't need that, it's better to use ArrayList, it's a drop-in replacement and won't incur in the performance penalty of synchronization.
- There's a simpler way to instantiate a
BufferedReader, using a FileReader instead of using an InputStreamReader plus a FileInputStream. Besides, FileReader will take care of pesky details regarding character encoding
- There's a simpler way to add elements to the last
List added to csvData, as shown in the code
- There's a simpler way to iterate through the
String[] returned by split(), using an enhanced loop
- Don't forget to close your streams! preferably inside a
finally block
If you don't need to add more elements to the returned List<List<String>>, you can use the following alternate version. It's faster because it avoids copying the String[] of split elements, but it won't allow adding new elements, as per the contract of asList():
private static List<List<String>> readTXTFile(String csvFileName) throws IOException {
String line = null;
BufferedReader stream = null;
List<List<String>> csvData = new ArrayList<List<String>>();
try {
stream = new BufferedReader(new FileReader(csvFileName));
while ((line = stream.readLine()) != null)
csvData.add(Arrays.asList(line.split(",")));
} finally {
if (stream != null)
stream.close();
}
return csvData;
}
