使用比较器而不添加类

Question

I am trying to sort an arraylist by string length, i know of implementing Comparator, but i was wondering if this could be done within my function, without adding any extra classes or methods? Ideally I want to output them shortest to longest, but that I can do!

Here is a snippet of the method i would like to implement the comparator with.

public static void sCompare(BufferedReader r, PrintWriter w) throws IOException {

    ArrayList<String> s= new ArrayList<String>();

    String line;
    int n = 0;
    while ((line = r.readLine()) != null) {
        s.add(line);
        n++;
    }
    //Collections.sort(s);  

    Iterator<String> i = s.iterator();
    while (i.hasNext()) {
        w.println(i.next());
    }
  }

Thanks in advance for any input!

Answer 1

I don't see anything wrong with implementing the Comparator interface. If your only concern is doing everything in the function, you could use an anonymous implementation. Something along the lines of :

    Collections.sort(s, new Comparator<String>() {
        @Override
        public int compare(String o1, String o2) {
            return o1.length() - o2.length();
        }
    });  

(that would replace you current line //Collections.sort(s); )

PS : you never use the value of n .

PPS: You may have to invert o1 and o2 depending of the order you want in the return statement.

Another example of implementing an interface with an anonymous class

Answer 2

I'm going to assume by "class" you mean "top level class", thus allowing the use of an anonymous class :

Collections.sort(s, new Comparator<String>() {
    public int compare(String a, String b) {
        // java 1.7:
        return Integer.compare(a.length(), b.length());
        // java 1.6
        return a.length() - b.length();
    }
});