用Java输入数组最有效的方法是什么？

Question

I need to read an array stored in a single line in a text file. What am doing till now is this:

BufferedReader in = /*hook it to the file input stream via an InputStreamReader  */
String[] input = in.readLine().split(" ");
for (int i = 0; i < input.length; i++) 
     array[i] = Integer.parseInt(input[i]);

Here, am using the String array unnecessarily. How can I remove this redundant step?

Answer 1

If you can use the InputStream and the Scanner class, you can do something like:

Scanner scanner = new Scanner(inputStream);
List<Integer> list = new ArrayList<Integer>();
while(scanner.hasNext()) {
    list.add(scanner.nextInt());
}

Answer 2

BufferedReader in = /*hook it to the file input stream via an InputStreamReader  */
String input = in.readLine();
StringBuilder sb = new StringBuilder();
List<Integer> list = new LinkedList<>(); //yours array equivalent
for (int i = 0; i < input.length; i++) {
    char ch = input.charAt(i);
    if (ch == ' ') {
        list.add(Integer.parseInt(sb.toString()));
        sb.clear();
    } else {
        sb.append(ch);
    }
}

This way you don't need to create the redundant array. I think it's very similar to what split() method does, but it doesn't require to handle regular expressions so the performance should be much better in this case.