如何对List进行排序 <String> 根据字符串的长度并打印前N个元素

Question

Your program should read an input file (the first argument to your program). The first line contains the value of the number 'N' followed by multiple lines. You may assume that the input file is formatted correctly and the number on the first line ie 'N' is a valid positive integer.eg

This is my Input:

2
Hello World

CodeEval
Quick Fox
A
San Francisco

Desired Output should be:

San Francisco
Hello World

This is my code:

 class Longest
 {
public static void main(String args[]) throws FileNotFoundException  
{
    BufferedReader in = null;
    List<String> myList = new ArrayList<String>();
    try 
    {   
        in = new BufferedReader(new FileReader("C:\\filename.txt"));
        String str;
        while ((str = in.readLine()) != null) 
        {
            if (str.length() == 0) continue;                                

            myList.add(str);
        }
    } 
    catch (IOException e) 
    {
        e.printStackTrace();
    } 
    System.out.println("Contents of the ArrayList : "+myList);
    System.out.println("Size of the ArrayList : "+myList.size());
    String s = myList.remove(0);
    System.out.println(System.getProperty("line.separator"));
    System.out.println("Number of lines to be printed : "+s);
    System.out.println("After removing first element of ArrayList : "+myList);
    System.out.println("Size of the ArrayList : "+myList.size());               

    Comparator comparator=Collections.reverseOrder();                   
    Collections.sort(myList,comparator);
    System.out.println("After sorting ArrayList in Descending Order :"+myList);


    int x = Integer.parseInt(s);
    System.out.println(System.getProperty("line.separator"));


for (String s1 : myList) {
System.out.println(s1);
}
System.out.println(System.getProperty("line.separator"));

for(int i=0; i<x; i++){
        System.out.println(myList.get(i));
    }

}   

}

But i am getting this output:

San Francisco
Quick Fox

Where am i going wrong?

Answer 1

Tje default sorting, will sort the list according to the alphabetical index. If you want to sort for other criterias, like the length in your case, you must implement oyur own Comparator

    Comparator<String> x = new Comparator<String>()
    {
        @Override
        public int compare(String o1, String o2)
        {
            if(o1.length() > o2.length())
                return -1;

            if(o2.length() > o1.length())
                return 1;

            return 0;
        }
    };

    Collections.sort(mylist,  x);

Answer 2

In your code, You just remove the first item in your list (myList). The size of the list will then be 4. Then you soort the list in reverse order zo it's normal you get the output:

San Francisco
Quick Fox
Hello World
CodeEval
A

As far as I can see you just removed your first element so your output would contain 5 elements. I don't see why you would want to get the desired output. The output is reversed alphabetical.