Why can't you have a “List>” in Java? [duplicate]

Answer 1

I know this is an old question but I just wanted to share my idea.

Instead of making a List of Lists, I personally just make a List of Type[] (List listArray = new ArrayList();), I generate a separate List of just Type (List list = new ArrayList();), then .add(list.toArray()). This way, it's clearer and easier to read than the List of Lists syntax which is confusing.

For example, in a recent project where I had an input file where each line with only a "0" meant a new line in the original (it was an encryption algorithm):

String[] input = getInputContents(inFile);
List currentBuffer = new ArrayList();
List buffers = new ArrayList();

for(String line : input) {
    if(line.equals("0")) {
        buffers.add((String[])currentBuffer.toArray());
        currentBuffer = new ArrayList();
    } else {
        currentBuffer.add(line);
    }
}